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hello and welcome to the space telescope

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public lecture series tonight

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first light hunting for galaxies at the

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dawn of cosmic time by dr guido roberts

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borsani of ucla

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i'm your host dr frank summers of the

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office of public outreach here at the

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space telescope science institute and as

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always i want to thank our wonderful

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tech team thomas marufu and grant

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justice

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i also need to continue to remind you

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that we will be online only until

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our upcoming talks on october 4th the

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universe of dante alighieri by a

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descendant of dante alleghery spirello

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de sorego alegre this should be a

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massively interesting talk i'm really

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looking forward to it on november 1st

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black holes how do we see that which

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gives off no light

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from stephanie lamassa of the space

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telescope science institute

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and on december 6th

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high energy strong astronomy with the

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swift observatory by stephen kirby at

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penn state university we talk a lot

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about a lot of our space telescopes we

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have not

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yet had a talk from someone about the

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swift observatory so this should be a

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treat

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all this information is available on our

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website

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public hyphen lectures which will give

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you this web page you see here in front

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of you

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on the left side you can see the uh

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our webcasts both our youtube playlists

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and our webcast archive at space

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telescope science institute

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and on the right we have the box where

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you can enter your email address and

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also on that page are the list of the

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upcoming lectures

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and if you click on one of those

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lectures it will give you all the

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information about it including the

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description of the talk and after it has

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been presented we have the sdsdi webcast

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link and down at the bottom you can see

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our email is uh basically twice a month

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you get a reminder of things you can

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sign up on at the website as i showed

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you

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hubble space telescope all one word

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you will get the notices of new videos

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that we post on our channel and

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reminders of live events such as this

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finally if you have comments or

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questions you can send them to the email

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address public lecture

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our social media

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for the hubble space telescope the james

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webb space telescope and for the space

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telescope science institute is available

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on facebook twitter

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youtube and instagram

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i myself do a pathetically tiny

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nothing's worth of uh

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social media on facebook and twitter as

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and now the news from the universe for

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september 2022

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our first story

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betelgeuse blowout and if you are a

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regular viewer you remember that betel

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juice has been spoken up just a bit over

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the last couple years

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first of all let me remind you that

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betelgeuse is one of the very very very

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few stars that can actually be resolved

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it is the

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left shoulder of orion

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in the constellation orion and the left

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shoulder is betelgeuse

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and hubble uh you know here in 1994

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did an observation where it resolved

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that star as more than just a point of

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light it actually resolved the disk of

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belgius betelgeuse is a red supergiant

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star

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and if it were in place of our sun

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its atmosphere would extend out past the

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orbit of jupiter okay that's how huge it

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is and that's why hubble can actually

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resolve the disk of the star

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right

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but what the recent thing is that in

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2019 betelgeuse dimmed unusually right

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so this is an uh two observations of

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betelgeuse one from 2016 and one from

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2019 and you can see how much dimmer it

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is in 2019.

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uh betelgeuse regularly fluctuates up

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and down just a little bit

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but now it was at 40 percent of its

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regular brightness which is a

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significant uh dip in its brightness

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however when that happened

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betelgeuse did not change its general

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characteristics so this is a spectrum of

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betelgeuse

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the red line is from 2004

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and the black line is first from 2020

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and you can see that the dips and

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wiggles in this spectrum all of the

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absorption lines and emission features

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are this same it's just that in 2020

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they're at a lower level so it's the

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light from

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betelgeuse that has dimmed it is not the

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character essential character of the

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light that is actually changing

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so that led us to believe

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that instead of a major change in the

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star betel juice really that there was a

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cloud blocking it

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so the story we developed based upon the

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observations

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is that in

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2019 there was a blowout from

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uh from from betelgeuse probably a

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convective cell about a million miles

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across erupted through and blew out uh

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into space towards in the direction

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towards earth

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that material then cooled and turned

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into a dust cloud

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that blocked some of the light so from

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our point of view

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bail we were seeing view betelgeuse with

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this dark dusty cloud in front of it

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which blocked a lot of its light and

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dimmed the star betelgeuse but the star

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itself was not um did not suffer

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anything major

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all right and then it has since

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recovered

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and so you have to understand that as i

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said betelgeuse is a variable star and

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it regularly goes up and down up and

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down in its brightness over a small

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range over a 400 day period okay so this

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sine wave here is to represent the 400

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day brightness period

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relative to that here in red

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are the actual observations

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so you can see that in

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the left side here it's following its

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dip down and rise back up and then the

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explosion happens and then it dips way

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down okay this is down around forty

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percent of its uh its brightness so it's

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several magnitudes uh

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of to too faint um and then it rises

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back up as that cloud dissipates so it's

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now back up at its roughly average

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brightness

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but it hasn't fully recovered from this

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eruption because you can see it has not

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fully gone back into that standard 400

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day brightness period change this

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400-day variability and the 400-day

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variability is something that has been

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observed on betelgeuse for centuries

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okay so it's not a short-term effect

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this is a long-term thing so it did have

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a blowout um in night 2019 2020

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but and it is returned back to normal

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but not quite fully normal

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it doesn't have its long-term

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variability period

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re-established yet we will continue to

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second story

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turning cartwheels in the sky

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and i'm referring to

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the famous cartwheel galaxy

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and so this

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is resembling now not the cartwheel that

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the kids do when they turn over on

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in gymnastics

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but really a the wheel of a cart where

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you have these central hub and then you

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have the wheel around it here

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in this galaxy

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this is what's known as a ring galaxy

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and is believed to have been caused by a

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smaller galaxy

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popping right through the center

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creating a ripple uh

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effect that spreads across and and

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created this ring here

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uh you can see it has two companion

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galaxies here on the left uh neither one

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of them is believed to have been the

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small galaxy that popped through there's

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a third one that they called g3 that's

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off screen

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that

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the ring structure but it's a very

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beautiful structure here

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but this image from hubble was taken

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back in 1994

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with wide field planetary camera 2. um

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so well

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even by hubble standards it's a kind of

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crappy little image okay it's 600 pixels

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by 500 pixels um

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you can see that uh in the

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galaxies they're a little blown out this

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galaxy here uh its core is totally blown

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out you can't see any details here the

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center of the cartwheel's blown out so

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uh by today's observational standards

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and image processing standards uh this

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is not

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a great image

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however

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we have just observed this with the web

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space telescope and web gets a much

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better image

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yeah

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much much better okay

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uh the web image is four thousand by

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four thousand pixels much much higher

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resolution and is using a a brand new

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detector that is up there so

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there's your hubble

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uh visible light and there is web in

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infrared amazing sorts of details um and

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like most of the web images i've seen uh

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some of the coolest stuff is not the

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foreground say oh yeah the cartwheel

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galaxy's cool and these two galaxies are

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cool but look at all these background

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galaxies all right that's just

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fantastic detail in the background most

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every uh web image i've seen has this

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simply because the

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distant galaxies

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are redshifted a little bit and they

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show up better in infrared light so you

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get not only the sensitivity of the web

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detectors but you also get the advantage

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of looking in infrared and that pulls

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out those background galaxies

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but there's one thing i'd like to

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express to you a little bit more deeply

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about this because this is a combination

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of near-infrared imagery and

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mid-infrared imagery let me explain a

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little bit okay

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um so here is the um wavelength uh

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from 0.1 micron all the way up to a 100

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micron and that covers from the

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ultraviolet

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through the optical

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to the near infrared the mid infrared

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and all the way to the far infrared you

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know while optical covers just a small

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range of wavelengths you know about 400

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to 700 nanometers or

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0.4 to 0.7 microns here

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infrared covers a factor of over 100

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from

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less than one micron on up to a hundred

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microns okay so there's a lot larger in

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factors of wavelength change uh in the

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infrared

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such that

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we talk about the near infrared the part

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of the infrared that's nearest to the

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optical and then the mid-infrared and

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j2st as you can see covers both the near

285
00:12:22,069 --> 00:12:19,279
infrared and the mid-infrared and

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00:12:25,509 --> 00:12:22,079
because these are widely separated in

287
00:12:28,790 --> 00:12:25,519
you know uh you know from one from one

288
00:12:31,030 --> 00:12:28,800
to ten you can get a factor of 10 in

289
00:12:32,629 --> 00:12:31,040
wavelength difference they actually see

290
00:12:34,310 --> 00:12:32,639
different things and i just wanted to

291
00:12:37,030 --> 00:12:34,320
illustrate that with you with the

292
00:12:39,110 --> 00:12:37,040
cartwheel galaxy because we not only

293
00:12:41,509 --> 00:12:39,120
release the cartwheel galaxy with this

294
00:12:42,949 --> 00:12:41,519
combo combination near infrared and

295
00:12:44,949 --> 00:12:42,959
mid-infrared

296
00:12:46,949 --> 00:12:44,959
we also produced

297
00:12:48,629 --> 00:12:46,959
put it on our website in just

298
00:12:49,590 --> 00:12:48,639
the near infrared

299
00:12:51,670 --> 00:12:49,600
okay

300
00:12:53,110 --> 00:12:51,680
so if i go back to the

301
00:12:55,269 --> 00:12:53,120
combo image

302
00:12:58,230 --> 00:12:55,279
and then i go to the near infrared what

303
00:13:00,230 --> 00:12:58,240
do you see all that red the mid infrared

304
00:13:01,910 --> 00:13:00,240
was clear was called red in the previous

305
00:13:04,949 --> 00:13:01,920
images goes away

306
00:13:07,110 --> 00:13:04,959
all right and the gaseous structures

307
00:13:10,069 --> 00:13:07,120
that you see in the main cartwheel

308
00:13:13,190 --> 00:13:10,079
galaxy and one of the small companions

309
00:13:16,710 --> 00:13:13,200
go away and what you're really left with

310
00:13:19,269 --> 00:13:16,720
is stars near infrared is

311
00:13:23,110 --> 00:13:19,279
great for seeing the stellar structures

312
00:13:25,750 --> 00:13:23,120
right so if i go to the mid-infrared

313
00:13:28,870 --> 00:13:25,760
here's the mid-infrared image

314
00:13:30,710 --> 00:13:28,880
and you get that gaseous structure back

315
00:13:33,269 --> 00:13:30,720
but you lose the stars look at this

316
00:13:35,350 --> 00:13:33,279
small galaxy here right if i go back to

317
00:13:37,030 --> 00:13:35,360
the near infrared you see lots and lots

318
00:13:38,790 --> 00:13:37,040
of stars around it

319
00:13:41,910 --> 00:13:38,800
not so in the mid infrared the mid

320
00:13:44,310 --> 00:13:41,920
infrared does not see stars very well

321
00:13:46,710 --> 00:13:44,320
but it does see the gas so if i take for

322
00:13:49,110 --> 00:13:46,720
this and i go to the combo image

323
00:13:51,350 --> 00:13:49,120
you can see that that red that's air all

324
00:13:54,790 --> 00:13:51,360
that gas and dust structure in those two

325
00:13:56,790 --> 00:13:54,800
galaxies is what you see in the mid

326
00:13:57,910 --> 00:13:56,800
infrared

327
00:13:58,949 --> 00:13:57,920
so

328
00:14:00,069 --> 00:13:58,959
what you

329
00:14:01,509 --> 00:14:00,079
really want to do when you're

330
00:14:03,910 --> 00:14:01,519
understanding these images is

331
00:14:06,550 --> 00:14:03,920
recognizing that the near infrared and

332
00:14:09,430 --> 00:14:06,560
the mid infrared can see totally

333
00:14:11,590 --> 00:14:09,440
different structures in them all right

334
00:14:14,389 --> 00:14:11,600
the near infrared

335
00:14:16,470 --> 00:14:14,399
is the instrument it's called near cam

336
00:14:19,670 --> 00:14:16,480
and that's wavelengths from one to five

337
00:14:20,870 --> 00:14:19,680
microns uh and it sees the stars better

338
00:14:22,550 --> 00:14:20,880
than

339
00:14:25,670 --> 00:14:22,560
the other ones and it will be at a

340
00:14:27,269 --> 00:14:25,680
higher resolution okay uh this will be

341
00:14:29,829 --> 00:14:27,279
getting the four thousand by four

342
00:14:32,949 --> 00:14:29,839
thousand per uh image

343
00:14:35,750 --> 00:14:32,959
resolution the mid infrared which is the

344
00:14:37,509 --> 00:14:35,760
miri instrument uh goes generally from 5

345
00:14:40,629 --> 00:14:37,519
to 20 microns

346
00:14:42,870 --> 00:14:40,639
it sees the gas and dust better the gas

347
00:14:45,110 --> 00:14:42,880
and dust emit better in those

348
00:14:47,509 --> 00:14:45,120
wavelengths but it is of lower

349
00:14:49,509 --> 00:14:47,519
resolution uh and that's

350
00:14:52,310 --> 00:14:49,519
not due to the any fault of miri it's

351
00:14:55,030 --> 00:14:52,320
just the the fact that to gain

352
00:14:56,949 --> 00:14:55,040
resolution is determined by the size of

353
00:14:59,350 --> 00:14:56,959
your your

354
00:15:01,430 --> 00:14:59,360
mirror to the size of the wavelength and

355
00:15:03,350 --> 00:15:01,440
so for longer wavelengths the same

356
00:15:07,189 --> 00:15:03,360
mirror will only give you less

357
00:15:08,550 --> 00:15:07,199
resolution so by going up by a factor of

358
00:15:11,110 --> 00:15:08,560
5 or 10

359
00:15:13,189 --> 00:15:11,120
in the wavelengths that you're observing

360
00:15:15,750 --> 00:15:13,199
you're going to get that correspondingly

361
00:15:18,550 --> 00:15:15,760
less resolution so the miri instrument

362
00:15:20,870 --> 00:15:18,560
has less resolution than the near cam

363
00:15:23,110 --> 00:15:20,880
instrument but something to look out for

364
00:15:25,350 --> 00:15:23,120
in the james webb images as they are

365
00:15:27,590 --> 00:15:25,360
released because you get to see two

366
00:15:29,269 --> 00:15:27,600
different sides of the same object as

367
00:15:31,110 --> 00:15:29,279
well as we will generally produce a

368
00:15:34,550 --> 00:15:31,120
combined image that gives you both of

369
00:15:40,870 --> 00:15:36,870
and now back to our

370
00:15:45,430 --> 00:15:40,880
featured presentation uh guido roberts

371
00:15:47,990 --> 00:15:45,440
borsani is out at ucla in los angeles

372
00:15:50,230 --> 00:15:48,000
but he is originally from the uk

373
00:15:52,470 --> 00:15:50,240
uh he did his undergraduate degree at

374
00:15:54,230 --> 00:15:52,480
the university of kent although he did

375
00:15:55,430 --> 00:15:54,240
come to the states there i guess he

376
00:15:57,110 --> 00:15:55,440
maybe love

377
00:15:58,710 --> 00:15:57,120
developed a love for california he might

378
00:16:00,629 --> 00:15:58,720
have spent a year at university of

379
00:16:02,629 --> 00:16:00,639
california san diego

380
00:16:05,829 --> 00:16:02,639
but he was back in london university

381
00:16:09,350 --> 00:16:05,839
called luncheon to do his phd

382
00:16:11,350 --> 00:16:09,360
and then he came to uh ucla where he's

383
00:16:14,710 --> 00:16:11,360
been a postdoc there for the past three

384
00:16:15,829 --> 00:16:14,720
years um his main research well that's

385
00:16:17,910 --> 00:16:15,839
what he's going to talk to you about

386
00:16:21,350 --> 00:16:17,920
looking for galaxies at the dawn of

387
00:16:23,590 --> 00:16:21,360
cosmic time uh but he is also involved

388
00:16:27,110 --> 00:16:23,600
in one of the early release science

389
00:16:29,269 --> 00:16:27,120
observations for the web space telescope

390
00:16:31,430 --> 00:16:29,279
the glass project

391
00:16:34,310 --> 00:16:31,440
and so you'll probably be hearing from

392
00:16:37,030 --> 00:16:34,320
him or his team again in the near future

393
00:16:39,590 --> 00:16:37,040
with their results from that uh in his

394
00:16:42,389 --> 00:16:39,600
spare time he's very athletic he grew up

395
00:16:43,350 --> 00:16:42,399
playing soccer and uh doing all sorts of

396
00:16:46,550 --> 00:16:43,360
sports

397
00:16:48,150 --> 00:16:46,560
uh he's a surfer uh there in california

398
00:16:50,310 --> 00:16:48,160
he loves to go hiking which is another

399
00:16:51,509 --> 00:16:50,320
great thing to do in california so i'm

400
00:16:53,430 --> 00:16:51,519
not sure he's ever really going to want

401
00:16:54,870 --> 00:16:53,440
to leave california

402
00:16:57,910 --> 00:16:54,880
because he's got such great sports

403
00:16:59,990 --> 00:16:57,920
available to him he might have to uh but

404
00:17:01,990 --> 00:17:00,000
until then we're happy to have him here

405
00:17:07,990 --> 00:17:02,000
ladies and gentlemen dr guido robert

406
00:17:15,029 --> 00:17:11,270
well thank you very much uh frank for

407
00:17:16,630 --> 00:17:15,039
that wonderful introduction um it's my

408
00:17:19,029 --> 00:17:16,640
great pleasure to

409
00:17:22,789 --> 00:17:19,039
chat to you today um

410
00:17:24,309 --> 00:17:22,799
let me just share my screen uh over here

411
00:17:25,909 --> 00:17:24,319
there we go so it's it's my great

412
00:17:28,710 --> 00:17:25,919
pleasure to chat to you today i'd like

413
00:17:31,270 --> 00:17:28,720
to thank uh the organizers uh for giving

414
00:17:33,669 --> 00:17:31,280
me the opportunity uh to talk a little

415
00:17:36,390 --> 00:17:33,679
bit about the research that i'm doing

416
00:17:39,350 --> 00:17:36,400
over here at ucla it's a particularly

417
00:17:42,230 --> 00:17:39,360
exciting time uh with the arrival of uh

418
00:17:44,310 --> 00:17:42,240
the james webb space telescope and uh in

419
00:17:47,190 --> 00:17:44,320
particular what i'd like to do is take

420
00:17:48,870 --> 00:17:47,200
you right to uh the very edge of the

421
00:17:51,350 --> 00:17:48,880
observable universe and together we're

422
00:17:53,909 --> 00:17:51,360
going to go through a journey through

423
00:17:55,430 --> 00:17:53,919
about 96

424
00:17:57,909 --> 00:17:55,440
of cosmic time right to the very

425
00:17:59,990 --> 00:17:57,919
beginning of when the first stars in the

426
00:18:01,750 --> 00:18:00,000
first galaxies formed

427
00:18:03,430 --> 00:18:01,760
and what i'm going to talk to you about

428
00:18:05,830 --> 00:18:03,440
today is hopefully give you a little bit

429
00:18:08,150 --> 00:18:05,840
of a description of how we search for

430
00:18:10,390 --> 00:18:08,160
these galaxies why they're important and

431
00:18:12,710 --> 00:18:10,400
also how we've been using

432
00:18:14,630 --> 00:18:12,720
our foremost telescopes to really push

433
00:18:16,870 --> 00:18:14,640
the boundaries uh in terms of

434
00:18:19,110 --> 00:18:16,880
characterizing their properties and

435
00:18:21,830 --> 00:18:19,120
finally i'll try and end with a little

436
00:18:24,310 --> 00:18:21,840
bit of uh showcasing let's say the very

437
00:18:26,789 --> 00:18:24,320
first data that we've obtained with the

438
00:18:29,830 --> 00:18:26,799
james webb space telescope and how that

439
00:18:33,029 --> 00:18:29,840
telescope is um well revolutionizing

440
00:18:35,110 --> 00:18:33,039
early galaxy evolution already

441
00:18:38,150 --> 00:18:35,120
uh so to start off with as astronomers

442
00:18:40,710 --> 00:18:38,160
our aim really is to try and paint a

443
00:18:43,350 --> 00:18:40,720
coherent picture of the build-up of

444
00:18:45,430 --> 00:18:43,360
matter in the universe and

445
00:18:47,830 --> 00:18:45,440
through the eyes of our foremost

446
00:18:50,630 --> 00:18:47,840
telescopes we essentially can directly

447
00:18:52,950 --> 00:18:50,640
witness uh the past and what i mean by

448
00:18:55,270 --> 00:18:52,960
this is if you look on the left side of

449
00:18:57,750 --> 00:18:55,280
this screen for instance you can see

450
00:19:00,310 --> 00:18:57,760
two very large galaxies one at the top

451
00:19:01,750 --> 00:19:00,320
which is a spiral galaxy uh one at the

452
00:19:04,150 --> 00:19:01,760
bottom which is what we call an

453
00:19:07,270 --> 00:19:04,160
elliptical galaxy essentially just a

454
00:19:09,110 --> 00:19:07,280
sphere of a few stars it's not really

455
00:19:11,430 --> 00:19:09,120
forming many stars anymore it doesn't

456
00:19:14,070 --> 00:19:11,440
seem to have this beautiful ring-like

457
00:19:16,470 --> 00:19:14,080
structure that this milky way like

458
00:19:18,630 --> 00:19:16,480
star-forming galaxy at the top does and

459
00:19:22,070 --> 00:19:18,640
these two galaxies exist

460
00:19:24,950 --> 00:19:22,080
at the present day so uh 13.8 billion

461
00:19:26,870 --> 00:19:24,960
years after the big bang

462
00:19:30,070 --> 00:19:26,880
but if you just go a little bit further

463
00:19:31,990 --> 00:19:30,080
back to about six billion years

464
00:19:34,230 --> 00:19:32,000
after the big bang you can see that

465
00:19:36,310 --> 00:19:34,240
these galaxies look very very different

466
00:19:37,590 --> 00:19:36,320
so we've crossed a large fraction of

467
00:19:40,150 --> 00:19:37,600
cosmic time

468
00:19:42,390 --> 00:19:40,160
and you can see the galaxy at the top uh

469
00:19:43,590 --> 00:19:42,400
looks rather different to what we see on

470
00:19:45,669 --> 00:19:43,600
the left

471
00:19:48,070 --> 00:19:45,679
but it might be a precursor to this

472
00:19:50,310 --> 00:19:48,080
spiral galaxy whilst the galaxy is at

473
00:19:51,990 --> 00:19:50,320
the bottom might be precursors to the

474
00:19:53,350 --> 00:19:52,000
elliptical galaxies so i'm sure you'll

475
00:19:54,950 --> 00:19:53,360
agree they already

476
00:19:56,710 --> 00:19:54,960
look quite different but there seems to

477
00:19:58,470 --> 00:19:56,720
be a little bit of resemblance in terms

478
00:20:00,950 --> 00:19:58,480
of the structures

479
00:20:02,630 --> 00:20:00,960
uh on the right however if we look even

480
00:20:03,990 --> 00:20:02,640
further back in time so now we're

481
00:20:05,350 --> 00:20:04,000
crossing about

482
00:20:07,669 --> 00:20:05,360
96

483
00:20:10,230 --> 00:20:07,679
of cosmic time or so about 1 billion

484
00:20:12,390 --> 00:20:10,240
years after the big bang you can see

485
00:20:14,789 --> 00:20:12,400
that these galaxies now lose

486
00:20:16,549 --> 00:20:14,799
all resemblance really to the galaxies

487
00:20:18,789 --> 00:20:16,559
that we see in the present day you don't

488
00:20:21,190 --> 00:20:18,799
see any more lovely spiral arms you

489
00:20:23,029 --> 00:20:21,200
don't see any more real structure uh

490
00:20:24,310 --> 00:20:23,039
they're pretty much just these small

491
00:20:26,149 --> 00:20:24,320
blobs

492
00:20:28,390 --> 00:20:26,159
and this red that you see from the

493
00:20:30,149 --> 00:20:28,400
galaxies is not how they actually are if

494
00:20:31,430 --> 00:20:30,159
we were to travel to them uh they

495
00:20:35,430 --> 00:20:31,440
wouldn't be read this is just an

496
00:20:38,870 --> 00:20:35,440
artifact of um how we image them

497
00:20:41,909 --> 00:20:38,880
so why are why is it important for us to

498
00:20:44,789 --> 00:20:41,919
uh paint this uh a picture of cosmic

499
00:20:47,270 --> 00:20:44,799
history um it's good i think to put this

500
00:20:51,110 --> 00:20:47,280
into context a little bit so over here

501
00:20:53,750 --> 00:20:51,120
you can see uh the um history of the

502
00:20:55,750 --> 00:20:53,760
universe in graphic form uh with the age

503
00:20:57,750 --> 00:20:55,760
of the universe there at the bottom so

504
00:20:59,350 --> 00:20:57,760
on the left you have the

505
00:21:01,590 --> 00:20:59,360
big bang which we're all familiar with

506
00:21:03,990 --> 00:21:01,600
about 13.8

507
00:21:06,310 --> 00:21:04,000
billion years ago at time

508
00:21:08,310 --> 00:21:06,320
universal time equals zero straight

509
00:21:10,470 --> 00:21:08,320
after that you have this beautiful

510
00:21:11,750 --> 00:21:10,480
imprint called the cosmic microwave

511
00:21:14,470 --> 00:21:11,760
background

512
00:21:16,630 --> 00:21:14,480
uh which we imaged with wmap and also

513
00:21:18,310 --> 00:21:16,640
the planck satellites and this imprint

514
00:21:21,270 --> 00:21:18,320
is the imprint of the big bang this is

515
00:21:23,270 --> 00:21:21,280
what we see um and is characteristic of

516
00:21:25,270 --> 00:21:23,280
the large scale structure that we saw

517
00:21:27,750 --> 00:21:25,280
that we see today it's the seeds for

518
00:21:30,230 --> 00:21:27,760
that straight after that we enter a

519
00:21:31,669 --> 00:21:30,240
period called the cosmic dark ages over

520
00:21:33,350 --> 00:21:31,679
there this sort of

521
00:21:36,549 --> 00:21:33,360
dark stripe right in the middle over

522
00:21:38,310 --> 00:21:36,559
here there is a complete absence of uv

523
00:21:40,310 --> 00:21:38,320
sources there are no stars there are no

524
00:21:43,270 --> 00:21:40,320
galaxies all that exists

525
00:21:44,549 --> 00:21:43,280
for the time being are clouds of atomic

526
00:21:47,190 --> 00:21:44,559
hydrogen

527
00:21:48,789 --> 00:21:47,200
so let's let's call it a fog essentially

528
00:21:51,029 --> 00:21:48,799
of cosmic hydrogen

529
00:21:52,710 --> 00:21:51,039
but then approximately one billion years

530
00:21:54,310 --> 00:21:52,720
after the big bang the very first

531
00:21:57,669 --> 00:21:54,320
sources start to have formed the very

532
00:21:59,909 --> 00:21:57,679
first uv stars these stars then

533
00:22:01,669 --> 00:21:59,919
merge into globular clusters and these

534
00:22:02,630 --> 00:22:01,679
clusters then start forming the very

535
00:22:04,310 --> 00:22:02,640
small

536
00:22:06,230 --> 00:22:04,320
first galaxies that you saw in the

537
00:22:08,470 --> 00:22:06,240
previous image and crucially these

538
00:22:10,070 --> 00:22:08,480
galaxies start emitting a lot of uv

539
00:22:12,390 --> 00:22:10,080
light and this is important because this

540
00:22:14,710 --> 00:22:12,400
uv light ends up stripping

541
00:22:17,750 --> 00:22:14,720
the electron from the proton by the

542
00:22:19,750 --> 00:22:17,760
hydrogen atom and ionizes the universe

543
00:22:21,669 --> 00:22:19,760
uh into what we see today so you can see

544
00:22:24,310 --> 00:22:21,679
the very first sources start to form

545
00:22:25,669 --> 00:22:24,320
over here then through gravity uh they

546
00:22:27,909 --> 00:22:25,679
combine into bigger and bigger

547
00:22:29,909 --> 00:22:27,919
structures they put these ionized

548
00:22:32,230 --> 00:22:29,919
bubbles which you can see around them

549
00:22:34,470 --> 00:22:32,240
start to percolate to create bigger and

550
00:22:37,190 --> 00:22:34,480
bigger bubbles uh and then eventually

551
00:22:39,830 --> 00:22:37,200
all of this neutral hydrogen fog

552
00:22:42,310 --> 00:22:39,840
is um is ionized and you see the

553
00:22:43,909 --> 00:22:42,320
beautiful structure uh both in terms of

554
00:22:46,789 --> 00:22:43,919
the universe and also within the

555
00:22:49,669 --> 00:22:46,799
galaxies themselves that we see today

556
00:22:51,909 --> 00:22:49,679
so clearly the emergence of the first

557
00:22:55,270 --> 00:22:51,919
galaxies and the first stars is

558
00:22:56,070 --> 00:22:55,280
extremely important for how it impacted

559
00:22:59,190 --> 00:22:56,080
the

560
00:23:01,270 --> 00:22:59,200
universe into what we see today and uh

561
00:23:03,350 --> 00:23:01,280
this epoch is called the epoch of

562
00:23:06,470 --> 00:23:03,360
realization and this is going to form

563
00:23:08,710 --> 00:23:06,480
the basis uh for my talk today and if

564
00:23:10,310 --> 00:23:08,720
we're to take a slice of the universe at

565
00:23:12,230 --> 00:23:10,320
this particular time it might look

566
00:23:14,310 --> 00:23:12,240
something like this this is a small

567
00:23:16,470 --> 00:23:14,320
little video where you see essentially a

568
00:23:19,190 --> 00:23:16,480
sort of block of cheese let's say

569
00:23:21,590 --> 00:23:19,200
uh in terms of the universe and the dark

570
00:23:25,510 --> 00:23:21,600
clouds are this neutral hydrogen fog so

571
00:23:26,710 --> 00:23:25,520
this hydrogen is blocking the uv light

572
00:23:28,630 --> 00:23:26,720
of

573
00:23:31,750 --> 00:23:28,640
the galaxies it's absorbing it and it's

574
00:23:33,350 --> 00:23:31,760
essentially getting burnt let's say

575
00:23:34,870 --> 00:23:33,360
you can see those sources in the middle

576
00:23:36,310 --> 00:23:34,880
over there these yellow dots and you can

577
00:23:39,110 --> 00:23:36,320
see these bubbles getting bigger and

578
00:23:40,950 --> 00:23:39,120
bigger as time goes on until eventually

579
00:23:45,909 --> 00:23:40,960
all of that hydrogen is burnt away and

580
00:23:49,269 --> 00:23:47,669
so we want to characterize then these

581
00:23:51,590 --> 00:23:49,279
distant galaxies because clearly they

582
00:23:53,590 --> 00:23:51,600
had a profound effect on the universe as

583
00:23:55,110 --> 00:23:53,600
we see it today but what does that mean

584
00:23:57,029 --> 00:23:55,120
exactly when we say characterize a

585
00:23:58,950 --> 00:23:57,039
galaxy what does that mean well i think

586
00:24:01,029 --> 00:23:58,960
it's useful to try and understand a

587
00:24:03,350 --> 00:24:01,039
galaxy's composition what does a galaxy

588
00:24:05,750 --> 00:24:03,360
actually look like so this is an example

589
00:24:07,909 --> 00:24:05,760
galaxy in the local universe and you can

590
00:24:10,870 --> 00:24:07,919
see that it has quite a few components

591
00:24:14,630 --> 00:24:10,880
to it has some stars both young and old

592
00:24:17,669 --> 00:24:14,640
it has dust over here it's also got gas

593
00:24:18,950 --> 00:24:17,679
hydrogen gas for instance or gas from

594
00:24:20,950 --> 00:24:18,960
metals

595
00:24:22,230 --> 00:24:20,960
it also has a supermassive black hole

596
00:24:24,789 --> 00:24:22,240
right at the center which is this

597
00:24:27,269 --> 00:24:24,799
particularly luminous point and all of

598
00:24:29,430 --> 00:24:27,279
these things combine uh to give a

599
00:24:31,110 --> 00:24:29,440
particular light profile to the galaxy

600
00:24:33,830 --> 00:24:31,120
so that's what you're seeing over here

601
00:24:36,070 --> 00:24:33,840
this black curve essentially is the

602
00:24:38,070 --> 00:24:36,080
total light profile of a galaxy as a

603
00:24:40,310 --> 00:24:38,080
function of wavelength or frequency

604
00:24:41,430 --> 00:24:40,320
shall we say and on the y-axis you can

605
00:24:43,269 --> 00:24:41,440
see

606
00:24:44,630 --> 00:24:43,279
the brightness of that profile so you

607
00:24:46,630 --> 00:24:44,640
see the brightness at different

608
00:24:49,590 --> 00:24:46,640
wavelengths really changes and that's

609
00:24:52,070 --> 00:24:49,600
due to uh the composition of the galaxy

610
00:24:54,070 --> 00:24:52,080
you can see the individual contributions

611
00:24:56,149 --> 00:24:54,080
from young stars in blue over here in

612
00:24:58,870 --> 00:24:56,159
the ultraviolet when you start getting

613
00:25:01,029 --> 00:24:58,880
to the rest frame optical portion of the

614
00:25:03,590 --> 00:25:01,039
spectrum you can see old star

615
00:25:05,110 --> 00:25:03,600
contributions in red uh whilst

616
00:25:07,350 --> 00:25:05,120
underneath that you can also get the

617
00:25:09,350 --> 00:25:07,360
contributions from the gas that's in the

618
00:25:11,750 --> 00:25:09,360
galaxy let's say for instance hydrogen

619
00:25:13,669 --> 00:25:11,760
or carbon or oxygen and these create

620
00:25:15,269 --> 00:25:13,679
these peaks over here these emission

621
00:25:17,669 --> 00:25:15,279
lines

622
00:25:20,149 --> 00:25:17,679
and so overall that then creates this

623
00:25:22,710 --> 00:25:20,159
black profile that you see here

624
00:25:25,110 --> 00:25:22,720
but if we were to point out telescopes

625
00:25:28,390 --> 00:25:25,120
uh at a particular wavelength you know

626
00:25:30,789 --> 00:25:28,400
sort of blindly let's say trying to um

627
00:25:33,430 --> 00:25:30,799
trying to look at this portion of the

628
00:25:35,269 --> 00:25:33,440
galaxy spectrum we might be disappointed

629
00:25:37,830 --> 00:25:35,279
the reason for that is uh the effect

630
00:25:39,830 --> 00:25:37,840
that we call redshift the stretching of

631
00:25:42,070 --> 00:25:39,840
the universe so

632
00:25:44,070 --> 00:25:42,080
this is an example you have the earth

633
00:25:46,950 --> 00:25:44,080
over here you have the galaxy here in

634
00:25:49,350 --> 00:25:46,960
the middle uh which reside in space and

635
00:25:52,390 --> 00:25:49,360
as the universe expands from the big

636
00:25:54,789 --> 00:25:52,400
bang up until now uh you can see that it

637
00:25:56,630 --> 00:25:54,799
ends up stretching the space between the

638
00:25:58,710 --> 00:25:56,640
earth and the galaxy what this does is

639
00:26:00,470 --> 00:25:58,720
it stretches the

640
00:26:02,710 --> 00:26:00,480
spectrum to redder and redder

641
00:26:04,470 --> 00:26:02,720
wavelengths that is why the galaxy

642
00:26:06,310 --> 00:26:04,480
appears redder and redder the further

643
00:26:07,830 --> 00:26:06,320
away it is from earth

644
00:26:10,390 --> 00:26:07,840
and this is particularly important

645
00:26:12,390 --> 00:26:10,400
because it means if we are to look at

646
00:26:15,110 --> 00:26:12,400
the galaxy let's play that one more time

647
00:26:17,190 --> 00:26:15,120
in the ultraviolet for instance uh we

648
00:26:19,190 --> 00:26:17,200
would see it if it's close by but we

649
00:26:21,669 --> 00:26:19,200
might miss it when it's further away

650
00:26:23,590 --> 00:26:21,679
because the galaxy is no longer emitting

651
00:26:25,909 --> 00:26:23,600
light in the ultraviolet it's emitting

652
00:26:27,909 --> 00:26:25,919
it in the infrared and that's nicely

653
00:26:30,390 --> 00:26:27,919
highlighted in this schematic below

654
00:26:32,710 --> 00:26:30,400
where you can see that as redshift

655
00:26:34,710 --> 00:26:32,720
increases so the distance between the

656
00:26:36,710 --> 00:26:34,720
earth and the object the

657
00:26:39,430 --> 00:26:36,720
number that characterizes the stretching

658
00:26:41,269 --> 00:26:39,440
of the universe the light of the galaxy

659
00:26:44,230 --> 00:26:41,279
then shifts from the visible or the

660
00:26:46,789 --> 00:26:44,240
ultraviolet into the infrared

661
00:26:48,950 --> 00:26:46,799
but this is actually uh sort of useful

662
00:26:50,870 --> 00:26:48,960
because it's allowed us to develop quite

663
00:26:53,269 --> 00:26:50,880
a useful technique to try and confirm

664
00:26:55,190 --> 00:26:53,279
the distances to these very distant

665
00:26:57,750 --> 00:26:55,200
galaxies or the redshift redshift and

666
00:26:59,590 --> 00:26:57,760
distance essentially uh equals sort of

667
00:27:01,830 --> 00:26:59,600
more or less the same thing

668
00:27:03,510 --> 00:27:01,840
their proxy for for the two so this is

669
00:27:05,430 --> 00:27:03,520
called the lyman break

670
00:27:09,510 --> 00:27:05,440
technique this was pioneered by chuck

671
00:27:11,590 --> 00:27:09,520
steidel at caltech in the in the 90s

672
00:27:13,990 --> 00:27:11,600
and uh here at the top you can see again

673
00:27:15,990 --> 00:27:14,000
the light profile of a galaxy

674
00:27:18,389 --> 00:27:16,000
you can see on the right it's emitting

675
00:27:20,630 --> 00:27:18,399
light from stars but then all of a

676
00:27:21,909 --> 00:27:20,640
sudden you see this drop in the

677
00:27:23,909 --> 00:27:21,919
brightness

678
00:27:27,029 --> 00:27:23,919
characteristic of a distant galaxy and

679
00:27:29,669 --> 00:27:27,039
the reason for this is that um

680
00:27:32,710 --> 00:27:29,679
the uv light of galaxies gets blocked

681
00:27:35,190 --> 00:27:32,720
out by clouds of hydrogen

682
00:27:37,110 --> 00:27:35,200
that uh intervene between the galaxy

683
00:27:38,870 --> 00:27:37,120
itself and the line of sight so we

684
00:27:41,669 --> 00:27:38,880
talked about the epoch of reionization

685
00:27:44,389 --> 00:27:41,679
where uh the universe is bathed in this

686
00:27:46,470 --> 00:27:44,399
hydrogen fog that hydrogen fog blocks

687
00:27:49,510 --> 00:27:46,480
the uv light from that galaxy and

688
00:27:51,269 --> 00:27:49,520
because we know exactly where that drop

689
00:27:54,710 --> 00:27:51,279
is supposed to occur it's supposed to

690
00:27:56,389 --> 00:27:54,720
occur at 912 angstroms any light that

691
00:27:59,190 --> 00:27:56,399
comes from the galaxy that is more

692
00:28:01,669 --> 00:27:59,200
energetic so more in the uv than that

693
00:28:03,909 --> 00:28:01,679
particular wavelength will get absorbed

694
00:28:05,669 --> 00:28:03,919
so as the universe stretches this

695
00:28:07,750 --> 00:28:05,679
characteristic drop

696
00:28:09,430 --> 00:28:07,760
uh will shift more and more to the right

697
00:28:13,269 --> 00:28:09,440
and if you measure that this that

698
00:28:15,190 --> 00:28:13,279
difference between the 912 angstroms or

699
00:28:16,710 --> 00:28:15,200
it's about 0.09

700
00:28:18,710 --> 00:28:16,720
microns you can see there's a big

701
00:28:21,110 --> 00:28:18,720
difference between 0.09 microns here on

702
00:28:22,549 --> 00:28:21,120
the graph and about 1 microns over here

703
00:28:25,350 --> 00:28:22,559
where this drop actually is and that

704
00:28:26,789 --> 00:28:25,360
difference gives you the redshift now to

705
00:28:28,630 --> 00:28:26,799
highlight this a little bit better you

706
00:28:30,870 --> 00:28:28,640
can see the images that we would take

707
00:28:33,029 --> 00:28:30,880
with our telescopes

708
00:28:34,710 --> 00:28:33,039
over these three portions of the

709
00:28:37,190 --> 00:28:34,720
spectrum and this is called the drop out

710
00:28:39,669 --> 00:28:37,200
technique and you can see that

711
00:28:41,830 --> 00:28:39,679
if we look at the orange filter so this

712
00:28:43,990 --> 00:28:41,840
would be an image taken with

713
00:28:46,070 --> 00:28:44,000
the james webb space telescope we would

714
00:28:48,070 --> 00:28:46,080
see the galaxy perfectly in the postage

715
00:28:50,149 --> 00:28:48,080
stamp on the bottom right because it's

716
00:28:52,389 --> 00:28:50,159
emitting light over there that is not

717
00:28:54,230 --> 00:28:52,399
getting absorbed the same thing for the

718
00:28:55,669 --> 00:28:54,240
blue filter over here you see the light

719
00:28:57,269 --> 00:28:55,679
being emitted and we see the galaxy

720
00:28:59,269 --> 00:28:57,279
clearly in the middle of the image but

721
00:29:01,190 --> 00:28:59,279
then if you move to the pink filter over

722
00:29:04,310 --> 00:29:01,200
here where it's not measuring any flux

723
00:29:07,750 --> 00:29:04,320
or any any emit any um brightness from

724
00:29:09,990 --> 00:29:07,760
the galaxy the galaxy drops out so to

725
00:29:12,549 --> 00:29:10,000
speak of this filter and that's

726
00:29:14,470 --> 00:29:12,559
important because the location of this

727
00:29:16,870 --> 00:29:14,480
so-called drop tells you where this

728
00:29:18,789 --> 00:29:16,880
break is this lineman break which gives

729
00:29:19,830 --> 00:29:18,799
you the redshift or the distance of the

730
00:29:21,669 --> 00:29:19,840
galaxy

731
00:29:23,750 --> 00:29:21,679
so just to reiterate if you look on the

732
00:29:25,830 --> 00:29:23,760
right this is a nice sort of schematic

733
00:29:28,389 --> 00:29:25,840
let's say you have the galaxy at the top

734
00:29:30,470 --> 00:29:28,399
if it's emitting blue uv light that

735
00:29:33,269 --> 00:29:30,480
light then gets absorbed by the hydrogen

736
00:29:34,950 --> 00:29:33,279
cloud between the galaxy and ourselves

737
00:29:37,350 --> 00:29:34,960
but if the galaxy is emitting redder

738
00:29:40,230 --> 00:29:37,360
light at infrared infrared wavelengths

739
00:29:42,149 --> 00:29:40,240
that goes through and we then capture

740
00:29:44,470 --> 00:29:42,159
that image

741
00:29:47,110 --> 00:29:44,480
so it's quite important then to choose

742
00:29:49,190 --> 00:29:47,120
carefully which telescope you want to

743
00:29:51,430 --> 00:29:49,200
use to try and characterize your galaxy

744
00:29:53,750 --> 00:29:51,440
or determine uh the distance to it the

745
00:29:55,350 --> 00:29:53,760
reason for that being is you have to

746
00:29:56,950 --> 00:29:55,360
carefully understand which physical

747
00:29:58,710 --> 00:29:56,960
process

748
00:30:01,110 --> 00:29:58,720
you are looking at from the galaxy

749
00:30:03,269 --> 00:30:01,120
electromagnetic spectrum but equally you

750
00:30:05,510 --> 00:30:03,279
need to make sure that you are pointing

751
00:30:07,350 --> 00:30:05,520
in the correct um at the correct

752
00:30:09,830 --> 00:30:07,360
wavelength where those physical

753
00:30:11,830 --> 00:30:09,840
processes are going to

754
00:30:14,070 --> 00:30:11,840
emit

755
00:30:15,590 --> 00:30:14,080
so if we take the hubble space telescope

756
00:30:18,149 --> 00:30:15,600
for instance to try and confirm the

757
00:30:20,549 --> 00:30:18,159
distances to these galaxies the distance

758
00:30:23,510 --> 00:30:20,559
of a galaxy is a fundamental component

759
00:30:25,350 --> 00:30:23,520
to trying to characterize it we might

760
00:30:27,830 --> 00:30:25,360
take uh hubble so

761
00:30:30,710 --> 00:30:27,840
if you remember the example just before

762
00:30:33,510 --> 00:30:30,720
we had three different images we now can

763
00:30:35,510 --> 00:30:33,520
use the full assortment of um

764
00:30:38,070 --> 00:30:35,520
of optical and infrared filters from the

765
00:30:42,070 --> 00:30:38,080
hubble space telescope so here you see

766
00:30:44,070 --> 00:30:42,080
an example spectrum of a distant galaxy

767
00:30:47,430 --> 00:30:44,080
right here um where the mouse is

768
00:30:50,630 --> 00:30:47,440
pointing this is that 912 angstrom break

769
00:30:52,710 --> 00:30:50,640
which you will see so as the galaxy

770
00:30:54,149 --> 00:30:52,720
then gets redshifted further and further

771
00:30:55,909 --> 00:30:54,159
away from us

772
00:30:58,230 --> 00:30:55,919
you can see that the hydrogen is

773
00:31:00,710 --> 00:30:58,240
absorbing this light from the galaxy and

774
00:31:02,710 --> 00:31:00,720
it's creating this break and as it moves

775
00:31:04,789 --> 00:31:02,720
through these hubble filters these

776
00:31:06,389 --> 00:31:04,799
filters are what we use to take the

777
00:31:09,430 --> 00:31:06,399
images you can see that in the

778
00:31:12,149 --> 00:31:09,440
corresponding images below the galaxy

779
00:31:15,029 --> 00:31:12,159
drops out and that again is important

780
00:31:17,750 --> 00:31:15,039
because the location of this dropout

781
00:31:19,590 --> 00:31:17,760
tells you an approximate redshift or

782
00:31:22,389 --> 00:31:19,600
distance let's see

783
00:31:24,389 --> 00:31:22,399
so now that we know how to search for

784
00:31:25,990 --> 00:31:24,399
distant galaxies uh what sort of

785
00:31:28,549 --> 00:31:26,000
galaxies have we found which are the

786
00:31:30,549 --> 00:31:28,559
most distant galaxies that we

787
00:31:32,950 --> 00:31:30,559
know of

788
00:31:34,630 --> 00:31:32,960
i like this picture uh quite a lot i

789
00:31:37,269 --> 00:31:34,640
think this serves as a lot of

790
00:31:40,149 --> 00:31:37,279
inspiration for many astronomers this is

791
00:31:42,470 --> 00:31:40,159
the hubble ultra deep field so the

792
00:31:44,870 --> 00:31:42,480
hubble space telescope is or was our

793
00:31:47,269 --> 00:31:44,880
premier flagship telescope was launched

794
00:31:48,870 --> 00:31:47,279
in 1990s and it's been taking these

795
00:31:51,669 --> 00:31:48,880
stunning images

796
00:31:54,870 --> 00:31:51,679
of the universe ever since for us

797
00:31:57,590 --> 00:31:54,880
so in 2002 they installed the advanced

798
00:31:59,029 --> 00:31:57,600
camera for surveys acs instrument which

799
00:32:01,909 --> 00:31:59,039
is uh

800
00:32:05,269 --> 00:32:01,919
visible optical instrument let's say uh

801
00:32:07,830 --> 00:32:05,279
and in 2004 they pointed at the sky uh

802
00:32:10,389 --> 00:32:07,840
took um took an image

803
00:32:12,630 --> 00:32:10,399
for about a hundred different hours

804
00:32:16,630 --> 00:32:12,640
approximately this was supposed to be a

805
00:32:18,230 --> 00:32:16,640
blank area of the sky no larger than um

806
00:32:19,909 --> 00:32:18,240
if you take a a

807
00:32:21,750 --> 00:32:19,919
a pound coin

808
00:32:22,630 --> 00:32:21,760
and stretch it

809
00:32:25,269 --> 00:32:22,640
about

810
00:32:27,669 --> 00:32:25,279
an arm's length and look at the eye of

811
00:32:29,830 --> 00:32:27,679
the queen on on that pound coin uh it

812
00:32:31,110 --> 00:32:29,840
would be roughly that size area it's a

813
00:32:33,190 --> 00:32:31,120
tiny area

814
00:32:34,950 --> 00:32:33,200
and instead of revealing a blank sky

815
00:32:37,669 --> 00:32:34,960
with nothing in it what it revealed

816
00:32:39,350 --> 00:32:37,679
actually was thousands and thousands of

817
00:32:40,870 --> 00:32:39,360
galaxies and that's exactly what you're

818
00:32:43,350 --> 00:32:40,880
seeing here over here there are

819
00:32:45,750 --> 00:32:43,360
virtually no stars whatsoever what

820
00:32:48,230 --> 00:32:45,760
you're seeing are all galaxies

821
00:32:49,269 --> 00:32:48,240
approximately ten thousand uh in this

822
00:32:51,430 --> 00:32:49,279
image

823
00:32:53,269 --> 00:32:51,440
and if you use this so-called dropout

824
00:32:55,669 --> 00:32:53,279
technique then looking at the different

825
00:32:57,430 --> 00:32:55,679
images uh taken with the with the hubble

826
00:33:00,630 --> 00:32:57,440
space telescope over this area of the

827
00:33:03,430 --> 00:33:00,640
sky uh team uh revealed lots of

828
00:33:05,350 --> 00:33:03,440
different uh young galaxy candidates

829
00:33:07,830 --> 00:33:05,360
which were extremely far away

830
00:33:10,230 --> 00:33:07,840
approximately a few hundred million

831
00:33:12,870 --> 00:33:10,240
years after the big bang and you can see

832
00:33:15,909 --> 00:33:12,880
that they only resemble these sort of

833
00:33:17,509 --> 00:33:15,919
glob-like uh objects

834
00:33:20,070 --> 00:33:17,519
they don't appear to have very much

835
00:33:22,070 --> 00:33:20,080
structure again the red

836
00:33:24,870 --> 00:33:22,080
is not what they look like intrinsically

837
00:33:28,070 --> 00:33:24,880
this is just an artifact of of what what

838
00:33:28,440 --> 00:33:28,080
they of how we image them

839
00:33:30,630 --> 00:33:28,450
um

840
00:33:32,310 --> 00:33:30,640
[Music]

841
00:33:34,310 --> 00:33:32,320
and you can see that there are quite a

842
00:33:36,389 --> 00:33:34,320
few of them a lot more than one

843
00:33:40,549 --> 00:33:36,399
initially anticipated

844
00:33:43,110 --> 00:33:40,559
uh however again this is these redshifts

845
00:33:45,590 --> 00:33:43,120
are only approximate uh values they are

846
00:33:49,430 --> 00:33:45,600
approximate distances what really we

847
00:33:52,789 --> 00:33:49,440
need is spectroscopy so spectroscopy is

848
00:33:55,029 --> 00:33:52,799
the act of splitting up the lights over

849
00:33:57,350 --> 00:33:55,039
a finer wavelength grid so that we can

850
00:33:59,669 --> 00:33:57,360
really identify signatures within a

851
00:34:02,149 --> 00:33:59,679
spectrum rather than over a coarse

852
00:34:04,070 --> 00:34:02,159
wavelength grid that is given by

853
00:34:06,950 --> 00:34:04,080
imaging capabilities and what i mean by

854
00:34:11,909 --> 00:34:06,960
that is an example over here so the top

855
00:34:13,669 --> 00:34:11,919
you have um a galaxy spectrum not at

856
00:34:16,230 --> 00:34:13,679
the redshifts we're talking about of

857
00:34:18,869 --> 00:34:16,240
redshift 7 then above or so

858
00:34:20,550 --> 00:34:18,879
this is roughly redshifts of 2 which is

859
00:34:21,990 --> 00:34:20,560
still about half of the age of the

860
00:34:24,069 --> 00:34:22,000
universe or so

861
00:34:25,030 --> 00:34:24,079
at the top you can see

862
00:34:27,270 --> 00:34:25,040
these

863
00:34:29,109 --> 00:34:27,280
2d spectra taken with the keck

864
00:34:31,190 --> 00:34:29,119
telescopes on top of warner care in

865
00:34:34,629 --> 00:34:31,200
hawaii and these bright points

866
00:34:38,710 --> 00:34:34,639
correspond to emission lines so

867
00:34:41,510 --> 00:34:38,720
we are no longer looking at uh this uh

868
00:34:43,750 --> 00:34:41,520
this lyman break which covers a very

869
00:34:45,990 --> 00:34:43,760
coarse grid and this approximate

870
00:34:48,550 --> 00:34:46,000
distance but now we are pinpointing the

871
00:34:51,430 --> 00:34:48,560
distances with these very characteristic

872
00:34:54,310 --> 00:34:51,440
features uh from gas within the galaxies

873
00:34:56,629 --> 00:34:54,320
such as oxygen over here or hydrogen or

874
00:34:58,390 --> 00:34:56,639
nitrogen or sulfur for instance so it's

875
00:35:00,390 --> 00:34:58,400
a much more precise

876
00:35:03,190 --> 00:35:00,400
technique to try and pinpoint the

877
00:35:05,030 --> 00:35:03,200
distance of the galaxy however as we

878
00:35:06,710 --> 00:35:05,040
mentioned these galaxies are redshifted

879
00:35:09,270 --> 00:35:06,720
so a lot of these features when they're

880
00:35:12,950 --> 00:35:09,280
very very distant uh end up being

881
00:35:16,710 --> 00:35:12,960
outside of our telescope capabilities

882
00:35:19,190 --> 00:35:16,720
one emission line which still is visible

883
00:35:21,109 --> 00:35:19,200
from our telescopes on the ground is

884
00:35:23,109 --> 00:35:21,119
called the lyman alpha line and that's

885
00:35:25,750 --> 00:35:23,119
what you see at the bottom here this is

886
00:35:28,150 --> 00:35:25,760
a distant galaxy at a redshift of six

887
00:35:29,510 --> 00:35:28,160
approximately um so these distant

888
00:35:31,510 --> 00:35:29,520
galaxies that we're trying to look for

889
00:35:35,270 --> 00:35:31,520
at redshift 7 and above generally

890
00:35:37,670 --> 00:35:35,280
speaking and you can see this much finer

891
00:35:39,349 --> 00:35:37,680
grid of wavelengths if you want the

892
00:35:41,829 --> 00:35:39,359
y-axis shows the brightness of the

893
00:35:42,950 --> 00:35:41,839
galaxy the x-axis shows the wavelength

894
00:35:45,190 --> 00:35:42,960
and again you can see this

895
00:35:46,950 --> 00:35:45,200
characteristic drop that we were talking

896
00:35:49,990 --> 00:35:46,960
about which we look at with

897
00:35:52,950 --> 00:35:50,000
imaging but you can also see this larger

898
00:35:55,270 --> 00:35:52,960
peak over here and this peak is

899
00:35:57,510 --> 00:35:55,280
emission that comes from

900
00:36:00,550 --> 00:35:57,520
hydrogen this emission generally

901
00:36:02,150 --> 00:36:00,560
speaking however is uh occulted by the

902
00:36:04,790 --> 00:36:02,160
hydrogen along the line of site it's

903
00:36:07,430 --> 00:36:04,800
absorbed so the galaxies that reside

904
00:36:10,310 --> 00:36:07,440
within this hydrogen fog we typically

905
00:36:12,230 --> 00:36:10,320
don't expect to see this line however it

906
00:36:13,670 --> 00:36:12,240
is one of the only lines that we can

907
00:36:15,990 --> 00:36:13,680
look for for these ultra distant

908
00:36:18,310 --> 00:36:16,000
galaxies because they are at such high

909
00:36:21,349 --> 00:36:18,320
redshifts uh and we have to consider the

910
00:36:23,109 --> 00:36:21,359
capabilities of our telescopes

911
00:36:23,910 --> 00:36:23,119
so it's a little bit like trying to look

912
00:36:26,790 --> 00:36:23,920
for

913
00:36:29,589 --> 00:36:26,800
uh you know car headlights uh in a fog

914
00:36:32,310 --> 00:36:29,599
from uh you know the us and europe it's

915
00:36:34,710 --> 00:36:32,320
not exactly easy but this is what we try

916
00:36:39,670 --> 00:36:37,109
so we set out to try and confirm the

917
00:36:40,950 --> 00:36:39,680
distances in this way with the keck

918
00:36:43,030 --> 00:36:40,960
telescope

919
00:36:45,109 --> 00:36:43,040
about five-ish years ago

920
00:36:48,790 --> 00:36:45,119
we looked for the most distant galaxies

921
00:36:51,190 --> 00:36:48,800
we could possibly find at the time over

922
00:36:53,190 --> 00:36:51,200
what we call the candles fields the

923
00:36:55,349 --> 00:36:53,200
candles fields are

924
00:36:57,349 --> 00:36:55,359
different portions of the sky taken with

925
00:36:59,430 --> 00:36:57,359
deep hubble imaging you can see them

926
00:37:01,990 --> 00:36:59,440
here at the bottom right this schematic

927
00:37:03,589 --> 00:37:02,000
over here shows you the patches of um of

928
00:37:05,349 --> 00:37:03,599
the sky image with

929
00:37:07,190 --> 00:37:05,359
with the hubble space telescope and

930
00:37:09,190 --> 00:37:07,200
their size is relative to the moon so

931
00:37:11,349 --> 00:37:09,200
you can see it's a very small area of

932
00:37:13,589 --> 00:37:11,359
the sky but they are especially deep

933
00:37:15,829 --> 00:37:13,599
images so they're taken with very long

934
00:37:17,910 --> 00:37:15,839
exposures to try and find

935
00:37:20,630 --> 00:37:17,920
not just bright galaxies but also very

936
00:37:22,150 --> 00:37:20,640
fainter galaxies

937
00:37:23,430 --> 00:37:22,160
and so we used these fields that we

938
00:37:25,670 --> 00:37:23,440
tried to look for the most distant

939
00:37:28,550 --> 00:37:25,680
galaxies we could and lo and behold we

940
00:37:31,270 --> 00:37:28,560
found four galaxies using this so-called

941
00:37:32,790 --> 00:37:31,280
dropout technique um

942
00:37:34,630 --> 00:37:32,800
which suggested they would be at

943
00:37:36,550 --> 00:37:34,640
redshifts greater than seven greater

944
00:37:39,510 --> 00:37:36,560
than seven corresponds to just a few

945
00:37:41,829 --> 00:37:39,520
hundred million years after the big bang

946
00:37:43,910 --> 00:37:41,839
however these only remain candidates as

947
00:37:46,069 --> 00:37:43,920
long as they haven't been confirmed with

948
00:37:48,390 --> 00:37:46,079
spectroscopy with a spectrum looking for

949
00:37:50,630 --> 00:37:48,400
that signature lyman alpha line that

950
00:37:53,510 --> 00:37:50,640
comes from these star-forming

951
00:37:55,589 --> 00:37:53,520
galaxies and lo and behold we went out

952
00:37:58,310 --> 00:37:55,599
and we managed to find

953
00:38:00,390 --> 00:37:58,320
lyman alpha this small peak as you can

954
00:38:03,430 --> 00:38:00,400
see here in each of these four galaxies

955
00:38:05,030 --> 00:38:03,440
these spectra over here correspond to

956
00:38:05,910 --> 00:38:05,040
each of these four galaxies and at the

957
00:38:08,150 --> 00:38:05,920
time

958
00:38:09,670 --> 00:38:08,160
two of these broke the distance records

959
00:38:13,510 --> 00:38:09,680
for galaxies

960
00:38:15,829 --> 00:38:13,520
at redshifts of uh 7.7 and 8.6 so these

961
00:38:18,870 --> 00:38:15,839
were the most distant galaxies that we

962
00:38:21,750 --> 00:38:18,880
knew of at the time so four in total

963
00:38:23,990 --> 00:38:21,760
about five hours or more of spectroscopy

964
00:38:26,550 --> 00:38:24,000
with keck and four out of four of these

965
00:38:29,510 --> 00:38:26,560
show uh this lyman alpha line which

966
00:38:32,630 --> 00:38:29,520
suggests that there's no more hydrogen

967
00:38:34,390 --> 00:38:32,640
around these galaxies blocking that uv

968
00:38:36,950 --> 00:38:34,400
light

969
00:38:39,829 --> 00:38:36,960
we ended up taking this uh a little bit

970
00:38:42,230 --> 00:38:39,839
further however there was another galaxy

971
00:38:43,510 --> 00:38:42,240
called jd1 unfortunately we're not that

972
00:38:46,630 --> 00:38:43,520
inventive with

973
00:38:50,069 --> 00:38:46,640
names in astronomy jd1 is a galaxy that

974
00:38:51,750 --> 00:38:50,079
we thought was a redshift of nine or so

975
00:38:54,470 --> 00:38:51,760
you can you can see over here the

976
00:38:56,390 --> 00:38:54,480
postage stamps uh taken with the hubble

977
00:38:58,550 --> 00:38:56,400
space telescope again this drop out

978
00:39:00,950 --> 00:38:58,560
technique if you look at the red circle

979
00:39:03,430 --> 00:39:00,960
you can see that at infrared wavelengths

980
00:39:06,630 --> 00:39:03,440
the galaxy is very clear but then at

981
00:39:09,109 --> 00:39:06,640
optical wavelengths the galaxy drops out

982
00:39:10,030 --> 00:39:09,119
and it's because it drops out between

983
00:39:13,829 --> 00:39:10,040
this

984
00:39:18,069 --> 00:39:13,839
f105w and f125w which corresponds to

985
00:39:20,470 --> 00:39:18,079
about 1.05 and 1.25 microns that tells

986
00:39:23,270 --> 00:39:20,480
us that this characteristic break should

987
00:39:25,510 --> 00:39:23,280
be somewhere around here but because the

988
00:39:27,270 --> 00:39:25,520
imaging filters are very broad we don't

989
00:39:30,710 --> 00:39:27,280
know exactly where

990
00:39:33,109 --> 00:39:30,720
so we then set out on arduous journey to

991
00:39:36,230 --> 00:39:33,119
try and confirm uh the distance to this

992
00:39:39,109 --> 00:39:36,240
galaxy via spectroscopy

993
00:39:41,030 --> 00:39:39,119
myself and my two collaborators uh

994
00:39:43,030 --> 00:39:41,040
richard ellis and nicola lapocz at the

995
00:39:44,870 --> 00:39:43,040
time at university college london we

996
00:39:47,750 --> 00:39:44,880
went to the very large telescope in

997
00:39:50,069 --> 00:39:47,760
chile and we looked at this galaxy with

998
00:39:52,069 --> 00:39:50,079
more than eight hours uh with some of

999
00:39:55,750 --> 00:39:52,079
the world's foremost telescopes trying

1000
00:39:57,990 --> 00:39:55,760
to look for this lyman alpha line and lo

1001
00:39:59,990 --> 00:39:58,000
and behold we found this line as you can

1002
00:40:04,309 --> 00:40:00,000
see on the left this fairly clear line

1003
00:40:05,430 --> 00:40:04,319
which indicated a redshift of 9.1 or so

1004
00:40:08,470 --> 00:40:05,440
um

1005
00:40:10,630 --> 00:40:08,480
thereby confirming this galaxy as an

1006
00:40:12,390 --> 00:40:10,640
ultra distant galaxy

1007
00:40:14,550 --> 00:40:12,400
at the same time

1008
00:40:17,270 --> 00:40:14,560
our collaborators in japan had used the

1009
00:40:19,510 --> 00:40:17,280
alma telescope to look for a prominent

1010
00:40:21,430 --> 00:40:19,520
oxygen line which they found then on the

1011
00:40:24,550 --> 00:40:21,440
right suggesting that

1012
00:40:26,710 --> 00:40:24,560
this galaxy was actually quite young and

1013
00:40:29,109 --> 00:40:26,720
not only that but confirming the

1014
00:40:32,630 --> 00:40:29,119
redshifts fairly precisely so the oxygen

1015
00:40:36,069 --> 00:40:32,640
suggests that some young stars are

1016
00:40:37,670 --> 00:40:36,079
ionizing the oxygen around it

1017
00:40:40,630 --> 00:40:37,680
so at the time then this was the most

1018
00:40:43,349 --> 00:40:40,640
distant galaxy that we knew of which we

1019
00:40:46,309 --> 00:40:43,359
published this paper in 2018.

1020
00:40:48,230 --> 00:40:46,319
however that was not the end of uh this

1021
00:40:49,750 --> 00:40:48,240
story in terms of confirming the most

1022
00:40:53,910 --> 00:40:49,760
distant galaxies

1023
00:40:56,069 --> 00:40:53,920
um later on in about 2009 the hubble

1024
00:40:57,109 --> 00:40:56,079
ultra deep field infrared was combined

1025
00:40:59,670 --> 00:40:57,119
with the

1026
00:41:01,829 --> 00:40:59,680
optical data from the hubble ultra deep

1027
00:41:04,069 --> 00:41:01,839
field so now we're combining

1028
00:41:06,470 --> 00:41:04,079
infrared data from

1029
00:41:08,630 --> 00:41:06,480
hubble's flagship instrument the wide

1030
00:41:09,910 --> 00:41:08,640
field camera 3 which is an infrared

1031
00:41:11,030 --> 00:41:09,920
instrument

1032
00:41:13,829 --> 00:41:11,040
with the

1033
00:41:16,790 --> 00:41:13,839
bluer wavelengths of the optical filters

1034
00:41:19,109 --> 00:41:16,800
and hubble then

1035
00:41:21,910 --> 00:41:19,119
the team of observers combined all of

1036
00:41:24,309 --> 00:41:21,920
this data to create this beautiful image

1037
00:41:26,150 --> 00:41:24,319
over here called the extreme deep field

1038
00:41:27,190 --> 00:41:26,160
now just like the hubble ultra deep

1039
00:41:29,270 --> 00:41:27,200
field

1040
00:41:30,150 --> 00:41:29,280
there are virtually no stars in this

1041
00:41:33,589 --> 00:41:30,160
image

1042
00:41:36,950 --> 00:41:33,599
there are about 5 000 galaxies or so a

1043
00:41:39,589 --> 00:41:36,960
lot of them very very distant and uh

1044
00:41:41,589 --> 00:41:39,599
ultimately uh this covers about 30

1045
00:41:44,950 --> 00:41:41,599
millionth of the whole sky so it's a

1046
00:41:47,030 --> 00:41:44,960
tiny tiny portion of the entire sky

1047
00:41:48,950 --> 00:41:47,040
and this uh this team then set out to

1048
00:41:51,270 --> 00:41:48,960
look for these ultra distant galaxies

1049
00:41:54,710 --> 00:41:51,280
once again via this lyman break

1050
00:41:59,349 --> 00:41:57,349
and ended up finding four of these

1051
00:42:00,950 --> 00:41:59,359
galaxies you can see them over here

1052
00:42:02,870 --> 00:42:00,960
again

1053
00:42:05,510 --> 00:42:02,880
like we saw before they're these sort of

1054
00:42:08,309 --> 00:42:05,520
little blobs don't seem particularly

1055
00:42:11,190 --> 00:42:08,319
interesting uh but when you follow these

1056
00:42:13,990 --> 00:42:11,200
up with spectroscopy uh they are quite

1057
00:42:16,710 --> 00:42:14,000
interesting and this team did follow up

1058
00:42:19,190 --> 00:42:16,720
the galaxy this c component galaxy over

1059
00:42:22,390 --> 00:42:19,200
here which they thought was the best

1060
00:42:23,349 --> 00:42:22,400
candidate for a ultra distant galaxy and

1061
00:42:24,950 --> 00:42:23,359
uh

1062
00:42:27,230 --> 00:42:24,960
you can see a zoom in over here it does

1063
00:42:30,790 --> 00:42:27,240
not have a particularly imaginative name

1064
00:42:33,829 --> 00:42:30,800
gnz11 suggests that this galaxy might be

1065
00:42:35,829 --> 00:42:33,839
at a redshift of 10 or so and the team

1066
00:42:37,910 --> 00:42:35,839
went out then with the hubble space

1067
00:42:39,829 --> 00:42:37,920
telescope to get a spectrum not just

1068
00:42:42,069 --> 00:42:39,839
images but a spectrum

1069
00:42:43,190 --> 00:42:42,079
and this is what they found and you can

1070
00:42:44,870 --> 00:42:43,200
see that it's

1071
00:42:46,230 --> 00:42:44,880
first thing you might you might take

1072
00:42:48,550 --> 00:42:46,240
away from this image is that it's

1073
00:42:50,630 --> 00:42:48,560
actually very very challenging to get a

1074
00:42:53,829 --> 00:42:50,640
spectrum of these sort of galaxies and

1075
00:42:56,150 --> 00:42:53,839
to confirm their distances however this

1076
00:42:57,750 --> 00:42:56,160
also might remind you of

1077
00:43:00,630 --> 00:42:57,760
the spectrum that you saw before where

1078
00:43:02,630 --> 00:43:00,640
you see this characteristic break again

1079
00:43:05,670 --> 00:43:02,640
and this break over here tells you that

1080
00:43:09,270 --> 00:43:05,680
this galaxy actually is at a redshift of

1081
00:43:12,069 --> 00:43:09,280
11. so this corresponds roughly of about

1082
00:43:15,349 --> 00:43:12,079
400 million years after the big bang we

1083
00:43:19,270 --> 00:43:15,359
are now probing about 96

1084
00:43:24,309 --> 00:43:21,910
so can we perhaps age date these

1085
00:43:26,390 --> 00:43:24,319
galaxies now that we've confirmed uh

1086
00:43:28,230 --> 00:43:26,400
that they are ultra distant galaxies can

1087
00:43:30,230 --> 00:43:28,240
we perhaps say something about them

1088
00:43:32,550 --> 00:43:30,240
about their properties for instance how

1089
00:43:36,150 --> 00:43:32,560
old are their stars

1090
00:43:38,790 --> 00:43:36,160
uh the answer is in parts uh so if you

1091
00:43:41,270 --> 00:43:38,800
look at the light distribution of a

1092
00:43:44,069 --> 00:43:41,280
galaxy here in blue you can see that

1093
00:43:46,870 --> 00:43:44,079
this is matched by the brightness that's

1094
00:43:49,109 --> 00:43:46,880
measured in the hubble filters and again

1095
00:43:50,790 --> 00:43:49,119
you can see this characteristic break

1096
00:43:53,190 --> 00:43:50,800
now we know that

1097
00:43:55,270 --> 00:43:53,200
this imaging is influenced by the

1098
00:43:58,390 --> 00:43:55,280
intrinsic properties of the galaxies as

1099
00:44:00,550 --> 00:43:58,400
well as the gas that resides around the

1100
00:44:02,470 --> 00:44:00,560
galaxy itself so the gas that resides

1101
00:44:05,349 --> 00:44:02,480
around the galaxy itself gives rise to

1102
00:44:08,710 --> 00:44:05,359
this characteristic drop but at the same

1103
00:44:10,390 --> 00:44:08,720
time you might see that this um

1104
00:44:12,550 --> 00:44:10,400
that this point over here on the far

1105
00:44:14,710 --> 00:44:12,560
right seems boosted relative to the

1106
00:44:18,309 --> 00:44:14,720
others that means that the galaxy is far

1107
00:44:20,069 --> 00:44:18,319
brighter in this particular filter uh

1108
00:44:21,670 --> 00:44:20,079
than it is in any of the others these

1109
00:44:23,589 --> 00:44:21,680
last two filters by the way come from

1110
00:44:26,309 --> 00:44:23,599
the spitzer space telescope so here

1111
00:44:28,390 --> 00:44:26,319
we're combining hubble with spitzer

1112
00:44:30,390 --> 00:44:28,400
so this tells us something about the

1113
00:44:32,710 --> 00:44:30,400
underlying properties of the galaxies

1114
00:44:35,109 --> 00:44:32,720
and actually what this is telling us is

1115
00:44:37,349 --> 00:44:35,119
that this galaxy has very intense

1116
00:44:39,430 --> 00:44:37,359
nebular emission lines from oxygen so

1117
00:44:41,589 --> 00:44:39,440
it's saying that there are young stars

1118
00:44:44,390 --> 00:44:41,599
there prominent young stars that are

1119
00:44:47,430 --> 00:44:44,400
ionizing the oxygen around us in a crazy

1120
00:44:50,550 --> 00:44:47,440
fashion and uh this is giving rise to

1121
00:44:52,710 --> 00:44:50,560
this boosting of galaxy light in this

1122
00:44:54,710 --> 00:44:52,720
particular filter so we can try and

1123
00:44:57,190 --> 00:44:54,720
estimate them the ages of these young

1124
00:44:59,829 --> 00:44:57,200
stars via these lines

1125
00:45:02,069 --> 00:44:59,839
however this is not the only source for

1126
00:45:03,829 --> 00:45:02,079
this apparent boosting of

1127
00:45:06,470 --> 00:45:03,839
the light in this filter compared to the

1128
00:45:09,030 --> 00:45:06,480
others another one is what we call the

1129
00:45:11,990 --> 00:45:09,040
bomber break so the bomber break is

1130
00:45:13,829 --> 00:45:12,000
another one of these drops in brightness

1131
00:45:16,069 --> 00:45:13,839
that you can see over here these are

1132
00:45:18,390 --> 00:45:16,079
this is the spectrum of a galaxy at

1133
00:45:21,589 --> 00:45:18,400
different ages 20 million years followed

1134
00:45:24,230 --> 00:45:21,599
by 50 million years 100 and 500 million

1135
00:45:26,550 --> 00:45:24,240
years and you can see that clearly as a

1136
00:45:28,550 --> 00:45:26,560
function of age this drop becomes much

1137
00:45:30,630 --> 00:45:28,560
more prominent so what's happening over

1138
00:45:32,790 --> 00:45:30,640
here is that as a star gets older the

1139
00:45:35,829 --> 00:45:32,800
atmospheres of these stars are absorbing

1140
00:45:39,030 --> 00:45:35,839
the metals that are here and so that

1141
00:45:41,670 --> 00:45:39,040
absorption of the lights causes uh this

1142
00:45:44,230 --> 00:45:41,680
um this dipping of the flux over here

1143
00:45:46,309 --> 00:45:44,240
and if we're to over plot let's say all

1144
00:45:47,910 --> 00:45:46,319
the points that you see on the left over

1145
00:45:50,150 --> 00:45:47,920
here

1146
00:45:51,670 --> 00:45:50,160
you see that it gives actually uh more

1147
00:45:54,630 --> 00:45:51,680
or less the same

1148
00:45:57,829 --> 00:45:54,640
profile the same shape so one can ask

1149
00:45:59,349 --> 00:45:57,839
then if we take this this

1150
00:46:01,670 --> 00:45:59,359
distribution of light from the hubble

1151
00:46:03,910 --> 00:46:01,680
and spitzer space telescopes can we age

1152
00:46:06,550 --> 00:46:03,920
date the galaxies can we age date the

1153
00:46:09,910 --> 00:46:06,560
stars that are within these galaxies

1154
00:46:12,069 --> 00:46:09,920
so coming back to jd1 this galaxy that

1155
00:46:14,790 --> 00:46:12,079
we had looked at with

1156
00:46:17,670 --> 00:46:14,800
the vlt and with alma now that we have a

1157
00:46:20,630 --> 00:46:17,680
secure redshift we can actually map out

1158
00:46:23,030 --> 00:46:20,640
the underlying properties of

1159
00:46:25,349 --> 00:46:23,040
that galaxy and over here you can see

1160
00:46:27,270 --> 00:46:25,359
the total light profile in red

1161
00:46:30,069 --> 00:46:27,280
you can see this particular jump over

1162
00:46:32,630 --> 00:46:30,079
here and this jump can only be explained

1163
00:46:34,950 --> 00:46:32,640
if you uh if you have this young

1164
00:46:37,190 --> 00:46:34,960
component over here in blue as well as

1165
00:46:39,910 --> 00:46:37,200
this older component from more mature

1166
00:46:42,150 --> 00:46:39,920
stars that are not just a few tens of

1167
00:46:43,589 --> 00:46:42,160
millions of years old but a few hundred

1168
00:46:46,470 --> 00:46:43,599
million years old

1169
00:46:48,470 --> 00:46:46,480
and uh so we conducted a search for more

1170
00:46:51,030 --> 00:46:48,480
galaxies like this we found three of

1171
00:46:52,790 --> 00:46:51,040
them you can see similar uh sort of

1172
00:46:55,430 --> 00:46:52,800
technique similar analysis and you can

1173
00:46:57,270 --> 00:46:55,440
see that in each of these cases you are

1174
00:46:58,950 --> 00:46:57,280
seeing this jump between the last two

1175
00:47:02,069 --> 00:46:58,960
points and that jump can only be

1176
00:47:03,030 --> 00:47:02,079
explained by the presence of more mature

1177
00:47:05,109 --> 00:47:03,040
stars

1178
00:47:07,589 --> 00:47:05,119
but galaxies in general are expected to

1179
00:47:09,510 --> 00:47:07,599
be quite young they haven't had a

1180
00:47:12,230 --> 00:47:09,520
ton of time to evolve in the early

1181
00:47:13,750 --> 00:47:12,240
universe so do we expect these more

1182
00:47:15,589 --> 00:47:13,760
mature stars

1183
00:47:17,750 --> 00:47:15,599
or are these sort of flukes are they

1184
00:47:18,870 --> 00:47:17,760
representative of the

1185
00:47:21,510 --> 00:47:18,880
normal

1186
00:47:23,750 --> 00:47:21,520
star-forming population or not that

1187
00:47:25,109 --> 00:47:23,760
remains to be seen

1188
00:47:27,190 --> 00:47:25,119
we can then ask ourselves do the

1189
00:47:29,190 --> 00:47:27,200
earliest galaxies already have black

1190
00:47:32,630 --> 00:47:29,200
supermassive black holes in the local

1191
00:47:35,190 --> 00:47:32,640
universe we know uh we know that um most

1192
00:47:37,190 --> 00:47:35,200
galaxies host a supermassive black hole

1193
00:47:39,829 --> 00:47:37,200
uh and that this supermassive black hole

1194
00:47:42,950 --> 00:47:39,839
evolves as a galaxy evolves as well but

1195
00:47:44,470 --> 00:47:42,960
it's unclear when they started to form

1196
00:47:46,790 --> 00:47:44,480
so the way that we can look for this

1197
00:47:49,589 --> 00:47:46,800
again is with spectroscopy where we try

1198
00:47:52,549 --> 00:47:49,599
and find emission lines that

1199
00:47:54,230 --> 00:47:52,559
cannot be ionized by from the radiation

1200
00:47:56,710 --> 00:47:54,240
of regular stars they need something

1201
00:47:58,870 --> 00:47:56,720
more potent more powerful like a

1202
00:48:01,349 --> 00:47:58,880
supermassive black hole and some of

1203
00:48:03,910 --> 00:48:01,359
these lines include helium-2 for

1204
00:48:06,390 --> 00:48:03,920
instance so these are two examples uh

1205
00:48:08,470 --> 00:48:06,400
over here where you can see at the

1206
00:48:11,270 --> 00:48:08,480
bottom you see the yellow line this is

1207
00:48:14,710 --> 00:48:11,280
uh the signature of that helium 2 and at

1208
00:48:17,109 --> 00:48:14,720
the top you can see

1209
00:48:23,030 --> 00:48:17,119
uh you can see um

1210
00:48:29,270 --> 00:48:24,870
can you still can you still hear me

1211
00:48:35,109 --> 00:48:31,990
so at the top we can still hear you

1212
00:48:36,150 --> 00:48:35,119
thanks um so at the top of these two

1213
00:48:38,150 --> 00:48:36,160
spectra

1214
00:48:39,910 --> 00:48:38,160
the

1215
00:48:42,390 --> 00:48:39,920
spectra that are taken

1216
00:48:45,190 --> 00:48:42,400
with the vlt and the keck telescopes

1217
00:48:47,589 --> 00:48:45,200
that white dot is what corresponds to

1218
00:48:49,430 --> 00:48:47,599
the emission line at the bottom

1219
00:48:52,069 --> 00:48:49,440
that indicates the presence of a

1220
00:48:53,990 --> 00:48:52,079
supermassive black hole probably at the

1221
00:48:56,230 --> 00:48:54,000
bottom here you see another example this

1222
00:48:59,030 --> 00:48:56,240
is nitrogen five

1223
00:48:59,829 --> 00:48:59,040
another line which is not easily excited

1224
00:49:01,510 --> 00:48:59,839
by

1225
00:49:03,670 --> 00:49:01,520
star forming

1226
00:49:06,390 --> 00:49:03,680
galaxies with just normal stars but it

1227
00:49:09,510 --> 00:49:06,400
needs some extra energetic input so the

1228
00:49:11,190 --> 00:49:09,520
presence of these three lines suggests

1229
00:49:12,630 --> 00:49:11,200
that there might be some other

1230
00:49:15,109 --> 00:49:12,640
contribution

1231
00:49:17,430 --> 00:49:15,119
to ionize these lines other than just

1232
00:49:19,829 --> 00:49:17,440
regular star-forming

1233
00:49:23,190 --> 00:49:19,839
sources more likely supermassive black

1234
00:49:28,150 --> 00:49:25,109
another question then that we can also

1235
00:49:31,589 --> 00:49:28,160
ask is do these galaxies harbor a lot of

1236
00:49:34,309 --> 00:49:31,599
dust so dust is expected to come from

1237
00:49:37,829 --> 00:49:34,319
supernovae which comes from the

1238
00:49:40,470 --> 00:49:37,839
death of massive stars when they explode

1239
00:49:43,190 --> 00:49:40,480
their enriched guts so to speak

1240
00:49:44,710 --> 00:49:43,200
spread form and spread dust as well as

1241
00:49:45,910 --> 00:49:44,720
heavy metals into the interstellar

1242
00:49:48,470 --> 00:49:45,920
medium

1243
00:49:49,750 --> 00:49:48,480
and young galaxies are not expected

1244
00:49:52,309 --> 00:49:49,760
necessarily

1245
00:49:54,470 --> 00:49:52,319
to have copious amounts of dust

1246
00:49:55,589 --> 00:49:54,480
which is indicative of more of a mature

1247
00:49:59,430 --> 00:49:55,599
system

1248
00:50:01,750 --> 00:49:59,440
but nonetheless we set out with

1249
00:50:03,349 --> 00:50:01,760
the alma telescope in chile that's what

1250
00:50:06,309 --> 00:50:03,359
you can see at the bottom right over

1251
00:50:10,390 --> 00:50:06,319
here to try and look for this signature

1252
00:50:12,870 --> 00:50:10,400
of dust alma is a submillimeter

1253
00:50:14,470 --> 00:50:12,880
telescope you can see these arrays over

1254
00:50:16,710 --> 00:50:14,480
here it's characterized by these

1255
00:50:19,190 --> 00:50:16,720
individual arrays which work together to

1256
00:50:21,750 --> 00:50:19,200
create one much more massive uh

1257
00:50:24,470 --> 00:50:21,760
telescope and that's what you can see at

1258
00:50:26,950 --> 00:50:24,480
the top here we did find dust in a very

1259
00:50:29,750 --> 00:50:26,960
distant galaxy galaxy at eight point of

1260
00:50:32,150 --> 00:50:29,760
redshift of 8.4 corresponding to only

1261
00:50:33,990 --> 00:50:32,160
about four percent of the present age of

1262
00:50:36,069 --> 00:50:34,000
the universe and you can see on the left

1263
00:50:38,470 --> 00:50:36,079
this detection here in sort of white and

1264
00:50:40,549 --> 00:50:38,480
green of dust and if you over plot it

1265
00:50:41,829 --> 00:50:40,559
with the hubble image of the telescope

1266
00:50:43,750 --> 00:50:41,839
here on the right you can see that it

1267
00:50:45,349 --> 00:50:43,760
matches up perfectly

1268
00:50:47,589 --> 00:50:45,359
the same thing happens with another

1269
00:50:50,069 --> 00:50:47,599
galaxy at a redshift of eight or so and

1270
00:50:52,470 --> 00:50:50,079
you can see the exact same here at the

1271
00:50:54,390 --> 00:50:52,480
bottom independently verified by a

1272
00:50:58,390 --> 00:50:54,400
different team for another galaxy so it

1273
00:51:00,710 --> 00:50:58,400
seems like perhaps uh early galaxies uh

1274
00:51:03,030 --> 00:51:00,720
have more dust than we initially

1275
00:51:05,109 --> 00:51:03,040
expected so is this more evidence for

1276
00:51:08,790 --> 00:51:05,119
perhaps some sort of mature stellar

1277
00:51:11,270 --> 00:51:08,800
population uh in these galaxies

1278
00:51:13,190 --> 00:51:11,280
it seems ah like it might

1279
00:51:15,510 --> 00:51:13,200
another thing we can see is these

1280
00:51:17,589 --> 00:51:15,520
galaxies when we look at them at uh in

1281
00:51:21,670 --> 00:51:17,599
the local universe appear to have this

1282
00:51:23,270 --> 00:51:21,680
well-defined structure of spiral arms um

1283
00:51:25,670 --> 00:51:23,280
but when we look at more distant

1284
00:51:27,829 --> 00:51:25,680
galaxies they appear to be just blobs

1285
00:51:30,150 --> 00:51:27,839
they don't appear to have much of a disc

1286
00:51:31,910 --> 00:51:30,160
like structure uh or any kind of

1287
00:51:34,470 --> 00:51:31,920
rotation they're more dominated by

1288
00:51:36,790 --> 00:51:34,480
mergers galaxies colliding together this

1289
00:51:39,030 --> 00:51:36,800
sort of thing and if we take our

1290
00:51:40,790 --> 00:51:39,040
telescopes and we point several times at

1291
00:51:42,790 --> 00:51:40,800
different portions of the galaxy we can

1292
00:51:44,870 --> 00:51:42,800
get an emission line that looks like

1293
00:51:47,670 --> 00:51:44,880
this on the right you can see this peak

1294
00:51:50,390 --> 00:51:47,680
and that then tells us the redshift of

1295
00:51:52,470 --> 00:51:50,400
the galaxy at different parts of it

1296
00:51:53,750 --> 00:51:52,480
essentially now when we look at the

1297
00:51:57,030 --> 00:51:53,760
differences

1298
00:52:00,870 --> 00:51:57,040
um in the position of those lines across

1299
00:52:03,190 --> 00:52:00,880
the galaxy we can see whether the stars

1300
00:52:04,630 --> 00:52:03,200
and the or the gas in that galaxy is

1301
00:52:07,030 --> 00:52:04,640
moving in some way and for these

1302
00:52:08,870 --> 00:52:07,040
galaxies we might expect random motion

1303
00:52:10,630 --> 00:52:08,880
but we actually don't so what you see

1304
00:52:13,270 --> 00:52:10,640
over here each pixel

1305
00:52:15,190 --> 00:52:13,280
has a red shift measured and if it's red

1306
00:52:16,710 --> 00:52:15,200
it's going away from us whilst if it's

1307
00:52:19,270 --> 00:52:16,720
blue it's coming towards us and you can

1308
00:52:21,829 --> 00:52:19,280
see this very clear gradient in both of

1309
00:52:24,549 --> 00:52:21,839
these cases which suggests some clear

1310
00:52:27,190 --> 00:52:24,559
rotation of the galaxy not this kind of

1311
00:52:29,430 --> 00:52:27,200
turbulent motion which you might expect

1312
00:52:31,270 --> 00:52:29,440
if the galaxy didn't have a disk and

1313
00:52:33,750 --> 00:52:31,280
coming back to jd1 this very distant

1314
00:52:36,230 --> 00:52:33,760
galaxy that has mature stars you again

1315
00:52:37,910 --> 00:52:36,240
see this gradient over here so that begs

1316
00:52:40,390 --> 00:52:37,920
the question you know are galaxies all

1317
00:52:43,430 --> 00:52:40,400
really really young or actually do they

1318
00:52:45,109 --> 00:52:43,440
have some kind of structure um you know

1319
00:52:47,829 --> 00:52:45,119
are they really just small galaxies that

1320
00:52:49,430 --> 00:52:47,839
they may be a bit more massive they also

1321
00:52:51,109 --> 00:52:49,440
have young stars but they also have

1322
00:52:53,109 --> 00:52:51,119
older stars as well

1323
00:52:55,190 --> 00:52:53,119
they appear to have dust in them which

1324
00:52:57,510 --> 00:52:55,200
we wouldn't necessarily expect for very

1325
00:52:59,670 --> 00:52:57,520
young galaxies they also appear to have

1326
00:53:01,349 --> 00:52:59,680
signatures of supermassive black holes

1327
00:53:02,150 --> 00:53:01,359
and ultimately some disk structure as

1328
00:53:04,150 --> 00:53:02,160
well

1329
00:53:06,230 --> 00:53:04,160
but we've sort of reached now the limit

1330
00:53:09,510 --> 00:53:06,240
of what we can do with the hubble space

1331
00:53:12,549 --> 00:53:09,520
telescope and with spectroscopy from the

1332
00:53:16,230 --> 00:53:12,559
ground the reason for this is hubble uh

1333
00:53:19,349 --> 00:53:16,240
only probes up to about 1.6 microns

1334
00:53:20,549 --> 00:53:19,359
in its imaging capabilities and distant

1335
00:53:22,309 --> 00:53:20,559
galaxies

1336
00:53:23,990 --> 00:53:22,319
emits the majority of their light and

1337
00:53:25,510 --> 00:53:24,000
the majority of signatures from their

1338
00:53:27,510 --> 00:53:25,520
stars and their gas

1339
00:53:29,430 --> 00:53:27,520
at even longer wavelengths in what we

1340
00:53:31,510 --> 00:53:29,440
call the rest frame optical so hubble

1341
00:53:34,790 --> 00:53:31,520
can't probe galaxies further than it

1342
00:53:37,030 --> 00:53:34,800
currently is at redshifts of 10 or so

1343
00:53:39,190 --> 00:53:37,040
on the ground if we look at if we try

1344
00:53:42,549 --> 00:53:39,200
and get spectroscopy with infrared

1345
00:53:44,790 --> 00:53:42,559
telescopes we only probe uh about

1346
00:53:48,710 --> 00:53:44,800
up to about one to two microns or so but

1347
00:53:51,190 --> 00:53:48,720
we are uh affected strongly by

1348
00:53:53,430 --> 00:53:51,200
the atmosphere with of the earth which

1349
00:53:55,990 --> 00:53:53,440
is blocking a lot of the infrared light

1350
00:53:59,510 --> 00:53:56,000
so there is a need then for space-based

1351
00:54:01,109 --> 00:53:59,520
spectroscopy in the infrared um and lo

1352
00:54:01,990 --> 00:54:01,119
and behold then that

1353
00:54:04,309 --> 00:54:02,000
is

1354
00:54:05,589 --> 00:54:04,319
where the james webb space telescope

1355
00:54:07,750 --> 00:54:05,599
then um

1356
00:54:08,829 --> 00:54:07,760
comes into play so

1357
00:54:14,710 --> 00:54:08,839
uh

1358
00:54:16,950 --> 00:54:14,720
telescope is a much larger telescope

1359
00:54:18,710 --> 00:54:16,960
than the hubble space telescope um

1360
00:54:20,230 --> 00:54:18,720
created with 18 different mirror

1361
00:54:22,230 --> 00:54:20,240
segments as you can see in this little

1362
00:54:24,950 --> 00:54:22,240
movie over here the

1363
00:54:27,990 --> 00:54:24,960
uh the

1364
00:54:30,710 --> 00:54:28,000
mirror segments are protected by a five

1365
00:54:33,349 --> 00:54:30,720
layered heat shield uh the james webb

1366
00:54:35,990 --> 00:54:33,359
space telescope because it looks in the

1367
00:54:39,670 --> 00:54:36,000
infrared wavelengths has to be protected

1368
00:54:41,589 --> 00:54:39,680
by all sources of uh infrared radiation

1369
00:54:43,109 --> 00:54:41,599
including from the sun and including

1370
00:54:45,910 --> 00:54:43,119
from the earth because if you're trying

1371
00:54:47,829 --> 00:54:45,920
to look for extremely distant sources uh

1372
00:54:49,910 --> 00:54:47,839
in the early universe in the infrared

1373
00:54:52,069 --> 00:54:49,920
even small bits of infrared light that

1374
00:54:53,510 --> 00:54:52,079
hit the mirror could be interpreted as a

1375
00:54:56,470 --> 00:54:53,520
distant galaxy

1376
00:54:58,309 --> 00:54:56,480
since the web is such a big telescope it

1377
00:55:00,230 --> 00:54:58,319
was folded up as you can see here in

1378
00:55:03,109 --> 00:55:00,240
this little schematic and it was fit

1379
00:55:05,030 --> 00:55:03,119
then at the top of an ariane 5

1380
00:55:06,630 --> 00:55:05,040
rocket this is a european

1381
00:55:08,309 --> 00:55:06,640
rocket and it

1382
00:55:10,870 --> 00:55:08,319
blasted off then

1383
00:55:13,109 --> 00:55:10,880
on christmas last year

1384
00:55:14,710 --> 00:55:13,119
where it then started its one day

1385
00:55:16,789 --> 00:55:14,720
journey up to

1386
00:55:19,270 --> 00:55:16,799
what we call lagrange point two this

1387
00:55:21,589 --> 00:55:19,280
point in space uh where the orbits of

1388
00:55:24,230 --> 00:55:21,599
the planet create an essentially uh

1389
00:55:26,789 --> 00:55:24,240
neutral uh gravitational pull and the

1390
00:55:29,349 --> 00:55:26,799
telescope during its its month-long

1391
00:55:33,430 --> 00:55:29,359
journey to that point unfolded into what

1392
00:55:37,030 --> 00:55:33,440
you can see here uh in the uh video

1393
00:55:39,109 --> 00:55:37,040
uh and then began its six-month uh long

1394
00:55:41,109 --> 00:55:39,119
um commissioning to try and make sure

1395
00:55:42,950 --> 00:55:41,119
that everything had aligned properly

1396
00:55:45,270 --> 00:55:42,960
everything had unfolded properly and all

1397
00:55:46,470 --> 00:55:45,280
of the instruments uh were working uh

1398
00:55:48,950 --> 00:55:46,480
optimally

1399
00:55:51,589 --> 00:55:48,960
so you can see here just a nice

1400
00:55:53,670 --> 00:55:51,599
illustration of just how much bigger the

1401
00:55:56,549 --> 00:55:53,680
james webb space telescope is compared

1402
00:55:59,030 --> 00:55:56,559
to the hubble space telescope it has a

1403
00:56:01,589 --> 00:55:59,040
mirror that is about 6.5 meters in

1404
00:56:03,430 --> 00:56:01,599
diameter compared to hubble's 2.4 and

1405
00:56:06,710 --> 00:56:03,440
this is crucial because it allows for

1406
00:56:10,390 --> 00:56:06,720
about six times more collecting area uh

1407
00:56:12,549 --> 00:56:10,400
to to collect these uh infrared photons

1408
00:56:14,710 --> 00:56:12,559
it has um

1409
00:56:18,069 --> 00:56:14,720
four different primary uh instruments

1410
00:56:19,430 --> 00:56:18,079
over here of which uh we can use uh for

1411
00:56:21,589 --> 00:56:19,440
both um

1412
00:56:24,789 --> 00:56:21,599
uh spectroscopy in the infrared as well

1413
00:56:26,549 --> 00:56:24,799
as imaging in the infrared so to list

1414
00:56:28,549 --> 00:56:26,559
these four over here you can see near

1415
00:56:31,190 --> 00:56:28,559
cam here in the middle where you see

1416
00:56:33,910 --> 00:56:31,200
these uh sort of two larger segments

1417
00:56:36,309 --> 00:56:33,920
which are divided in four this is um

1418
00:56:38,150 --> 00:56:36,319
this is the flagship imager let's say in

1419
00:56:41,190 --> 00:56:38,160
the near in the the

1420
00:56:44,390 --> 00:56:41,200
infrared wavelength um bands from james

1421
00:56:47,750 --> 00:56:44,400
webb it extends what hubble is able to

1422
00:56:50,309 --> 00:56:47,760
see out to about 4.4 microns then we

1423
00:56:52,150 --> 00:56:50,319
have near spec on the left over here

1424
00:56:54,470 --> 00:56:52,160
again four different quadrants but this

1425
00:56:56,950 --> 00:56:54,480
is primarily um

1426
00:56:58,390 --> 00:56:56,960
a multi-object

1427
00:57:00,710 --> 00:56:58,400
spectrograph where

1428
00:57:02,390 --> 00:57:00,720
inside each of these quadrants we can

1429
00:57:04,230 --> 00:57:02,400
put uh

1430
00:57:05,510 --> 00:57:04,240
quite a lot of galaxies hundreds of

1431
00:57:07,829 --> 00:57:05,520
galaxies

1432
00:57:09,270 --> 00:57:07,839
and take a spectrum out from anywhere

1433
00:57:11,910 --> 00:57:09,280
between

1434
00:57:15,349 --> 00:57:11,920
about 0.6 to 5 microns thereby getting

1435
00:57:17,510 --> 00:57:15,359
the full rest frame uv and full and most

1436
00:57:18,630 --> 00:57:17,520
of the rest frame optical of distant

1437
00:57:21,430 --> 00:57:18,640
galaxies

1438
00:57:23,829 --> 00:57:21,440
we also have nearest over here nearest

1439
00:57:26,470 --> 00:57:23,839
is a slitless spectrograph an imager and

1440
00:57:28,549 --> 00:57:26,480
what this means is you don't

1441
00:57:30,870 --> 00:57:28,559
position the spectrograph on a

1442
00:57:32,789 --> 00:57:30,880
particular galaxy you point it at a

1443
00:57:36,230 --> 00:57:32,799
particular point in space and you end up

1444
00:57:38,789 --> 00:57:36,240
getting a spectrum for each object that

1445
00:57:41,670 --> 00:57:38,799
is in that field of view

1446
00:57:44,870 --> 00:57:41,680
last one over here is miri miri

1447
00:57:47,430 --> 00:57:44,880
is a far infrared uh imager and low

1448
00:57:50,150 --> 00:57:47,440
resolution spectrograph it can do these

1449
00:57:53,510 --> 00:57:50,160
it can take images and take spectroscopy

1450
00:57:55,829 --> 00:57:53,520
up from about 5 microns to 25 microns so

1451
00:57:58,309 --> 00:57:55,839
it's really extending everything that

1452
00:58:01,030 --> 00:57:58,319
we've been able to do so far with hubble

1453
00:58:03,109 --> 00:58:01,040
and uh with um

1454
00:58:05,829 --> 00:58:03,119
with our ground-based telescopes like

1455
00:58:06,870 --> 00:58:05,839
keck and the vlt for instance

1456
00:58:09,270 --> 00:58:06,880
and so

1457
00:58:11,910 --> 00:58:09,280
uh this is a nice illustration i think

1458
00:58:14,069 --> 00:58:11,920
what we're able to get now with the

1459
00:58:16,470 --> 00:58:14,079
james webb space telescope since it

1460
00:58:19,270 --> 00:58:16,480
probes these much needed uh infrared

1461
00:58:21,190 --> 00:58:19,280
regions so this is an example spectrum

1462
00:58:24,630 --> 00:58:21,200
of a very distant galaxy a galaxy at

1463
00:58:27,510 --> 00:58:24,640
about redshift 7.5 or so and all of a

1464
00:58:30,069 --> 00:58:27,520
sudden all of these features here which

1465
00:58:32,470 --> 00:58:30,079
we couldn't access before are now

1466
00:58:34,630 --> 00:58:32,480
available to us so we can get

1467
00:58:37,510 --> 00:58:34,640
information about ionized bubbles so

1468
00:58:39,750 --> 00:58:37,520
whether the galaxy has ionized its uh

1469
00:58:42,230 --> 00:58:39,760
immediate surroundings via this lyman

1470
00:58:44,069 --> 00:58:42,240
alpha line and the lyman break which you

1471
00:58:46,789 --> 00:58:44,079
can see over here we can also get

1472
00:58:48,549 --> 00:58:46,799
information whether this galaxy has

1473
00:58:50,789 --> 00:58:48,559
super massive black holes in the middle

1474
00:58:53,349 --> 00:58:50,799
from these high excitation lines like

1475
00:58:55,190 --> 00:58:53,359
helium 2 and nitrogen 5. we can get the

1476
00:58:56,950 --> 00:58:55,200
star formation rates of the galaxies by

1477
00:58:57,990 --> 00:58:56,960
this sort of empty portion of the

1478
00:59:00,470 --> 00:58:58,000
spectrum

1479
00:59:03,190 --> 00:59:00,480
number of ionizing photons the stellar

1480
00:59:05,109 --> 00:59:03,200
ages of these galaxies over here uh

1481
00:59:08,309 --> 00:59:05,119
whether the galaxies harbor heavy metals

1482
00:59:10,069 --> 00:59:08,319
or not and also the stellar masses of

1483
00:59:13,349 --> 00:59:10,079
these galaxies

1484
00:59:14,950 --> 00:59:13,359
um so i was fortunate enough to be at

1485
00:59:17,109 --> 00:59:14,960
the launch of the james webb space

1486
00:59:20,630 --> 00:59:17,119
telescope and on the day

1487
00:59:21,670 --> 00:59:20,640
you go out uh onto this uh platform this

1488
00:59:23,430 --> 00:59:21,680
sort of

1489
00:59:25,190 --> 00:59:23,440
rainy gray day hoping that the launch

1490
00:59:27,349 --> 00:59:25,200
isn't gonna be uh

1491
00:59:30,150 --> 00:59:27,359
scrapped and then you

1492
00:59:32,309 --> 00:59:30,160
uh wait three seconds for that countdown

1493
00:59:35,430 --> 00:59:32,319
and after three seconds you see this

1494
00:59:36,870 --> 00:59:35,440
great big ball of flame emerge from

1495
00:59:38,870 --> 00:59:36,880
the horizon

1496
00:59:40,950 --> 00:59:38,880
you tend to experience a little bit of a

1497
00:59:43,670 --> 00:59:40,960
roller coaster of emotions for many this

1498
00:59:44,390 --> 00:59:43,680
is a lifetime uh of work and dedication

1499
00:59:48,309 --> 00:59:44,400
so

1500
00:59:51,109 --> 00:59:48,319
nervousness

1501
00:59:52,870 --> 00:59:51,119
even fear to a certain degree are all

1502
00:59:55,430 --> 00:59:52,880
very palpable

1503
00:59:57,990 --> 00:59:55,440
and uh the launch only really lasts a

1504
01:00:00,950 --> 00:59:58,000
few seconds

1505
01:00:03,750 --> 01:00:00,960
but the rumble you know of the ariane 5

1506
01:00:06,870 --> 01:00:03,760
rockets really continues uh for minutes

1507
01:00:09,270 --> 01:00:06,880
uh until you know even after the um the

1508
01:00:10,870 --> 01:00:09,280
telescope has or the rocket has uh

1509
01:00:14,390 --> 01:00:10,880
cleared the clouds

1510
01:00:16,710 --> 01:00:14,400
and um once the james webb then arrived

1511
01:00:19,030 --> 01:00:16,720
at its destination and started taking

1512
01:00:21,990 --> 01:00:19,040
images it revealed images that we could

1513
01:00:24,069 --> 01:00:22,000
only dream of this is an image taken a

1514
01:00:25,910 --> 01:00:24,079
test exposure taken with the james webb

1515
01:00:28,309 --> 01:00:25,920
fine guidance sensor so the instrument

1516
01:00:31,349 --> 01:00:28,319
that it uses to make sure it's pointing

1517
01:00:33,270 --> 01:00:31,359
at the right uh area of the sky and it

1518
01:00:36,150 --> 01:00:33,280
became instantly after i think this was

1519
01:00:38,470 --> 01:00:36,160
a 32-hour exposure one of the sharpest

1520
01:00:40,549 --> 01:00:38,480
and one of the deepest infrared images

1521
01:00:43,430 --> 01:00:40,559
uh taken at the time and again you can

1522
01:00:46,549 --> 01:00:43,440
see there are a few stars over here

1523
01:00:48,870 --> 01:00:46,559
but primarily what you see is this

1524
01:00:50,789 --> 01:00:48,880
this sea of galaxies in the background

1525
01:00:53,030 --> 01:00:50,799
of which no doubt there will be some

1526
01:00:55,430 --> 01:00:53,040
extremely distant galaxies and just to

1527
01:00:58,870 --> 01:00:55,440
highlight

1528
01:01:01,109 --> 01:00:58,880
quite starkly i think how the resolution

1529
01:01:03,750 --> 01:01:01,119
of hubble's spatial resolution of

1530
01:01:05,589 --> 01:01:03,760
hubble's capabilities has it has already

1531
01:01:07,270 --> 01:01:05,599
revolutionized sorry of the james webb

1532
01:01:09,589 --> 01:01:07,280
space telescope has already

1533
01:01:11,670 --> 01:01:09,599
revolutionized what we can see on here

1534
01:01:13,589 --> 01:01:11,680
you at the bottom you can see a

1535
01:01:16,470 --> 01:01:13,599
comparison between our previous

1536
01:01:18,630 --> 01:01:16,480
telescopes and james webb miri on the

1537
01:01:20,630 --> 01:01:18,640
right you have spitzer in the middle and

1538
01:01:22,710 --> 01:01:20,640
on the left you have the wise

1539
01:01:24,390 --> 01:01:22,720
telescope and you can see how on the

1540
01:01:26,309 --> 01:01:24,400
left you see a few of the brightest

1541
01:01:28,470 --> 01:01:26,319
sources but there's insufficient

1542
01:01:30,630 --> 01:01:28,480
resolution to um

1543
01:01:32,549 --> 01:01:30,640
to look for anything over there but then

1544
01:01:34,309 --> 01:01:32,559
james webb you get a whole lot more

1545
01:01:37,190 --> 01:01:34,319
detail

1546
01:01:39,190 --> 01:01:37,200
so on july 11th the first science grade

1547
01:01:41,910 --> 01:01:39,200
images were revealed the web's first

1548
01:01:44,950 --> 01:01:41,920
deep field and this image was truly

1549
01:01:47,670 --> 01:01:44,960
stunning about 12.5 hours of near cam

1550
01:01:49,589 --> 01:01:47,680
imaging over a galaxy cluster over here

1551
01:01:52,390 --> 01:01:49,599
you can see these uh

1552
01:01:54,230 --> 01:01:52,400
so-called einstein rings which is

1553
01:01:55,349 --> 01:01:54,240
essentially background galaxies which

1554
01:01:57,510 --> 01:01:55,359
are being

1555
01:02:00,390 --> 01:01:57,520
stretched and amplified due to the

1556
01:02:02,789 --> 01:02:00,400
strong gravitational pull of these

1557
01:02:05,029 --> 01:02:02,799
galaxies here in the middle

1558
01:02:07,349 --> 01:02:05,039
and not only did james webb look with

1559
01:02:09,589 --> 01:02:07,359
neocam it also looked with near spec and

1560
01:02:12,230 --> 01:02:09,599
this highlights exactly what i was

1561
01:02:14,710 --> 01:02:12,240
trying to uh showcase beforehand where

1562
01:02:17,829 --> 01:02:14,720
all of a sudden we now don't rely just

1563
01:02:20,309 --> 01:02:17,839
on this lyman alpha line at about one

1564
01:02:22,309 --> 01:02:20,319
micron or so to confirm the distance of

1565
01:02:24,470 --> 01:02:22,319
these ultra distant galaxies but now

1566
01:02:26,789 --> 01:02:24,480
we're all of a sudden getting oxygen

1567
01:02:29,990 --> 01:02:26,799
hydrogen even neon

1568
01:02:31,589 --> 01:02:30,000
and all of these now serve as indicators

1569
01:02:33,430 --> 01:02:31,599
to confirm the redshifts or the

1570
01:02:35,829 --> 01:02:33,440
distances to these galaxies and tell us

1571
01:02:38,230 --> 01:02:35,839
something about their ages as well as

1572
01:02:40,549 --> 01:02:38,240
the metalistics um you know and a

1573
01:02:42,150 --> 01:02:40,559
plethora of other things and just to

1574
01:02:44,950 --> 01:02:42,160
show you a comparison this is one of the

1575
01:02:47,109 --> 01:02:44,960
best spectra we have of a redshift uh

1576
01:02:49,270 --> 01:02:47,119
eight galaxy so the same redshift as

1577
01:02:51,670 --> 01:02:49,280
this particular galaxy here and you can

1578
01:02:53,990 --> 01:02:51,680
see the difference both in quality and

1579
01:02:56,309 --> 01:02:54,000
in terms of indicators that we get so

1580
01:02:58,150 --> 01:02:56,319
james webb is already blowing things out

1581
01:03:00,870 --> 01:02:58,160
of the water

1582
01:03:04,150 --> 01:03:00,880
so i am part of the

1583
01:03:05,190 --> 01:03:04,160
through the looking glass jwst ers

1584
01:03:09,430 --> 01:03:05,200
program

1585
01:03:13,190 --> 01:03:09,440
first and the deepest extra extra

1586
01:03:15,910 --> 01:03:13,200
galactic data of the entire ers campaign

1587
01:03:17,190 --> 01:03:15,920
the idea is to target another galaxy

1588
01:03:18,950 --> 01:03:17,200
cluster which you can see here on the

1589
01:03:21,190 --> 01:03:18,960
left with nearest and near spec

1590
01:03:24,710 --> 01:03:21,200
spectroscopy um

1591
01:03:26,549 --> 01:03:24,720
as well as near cam imaging of a um of a

1592
01:03:28,789 --> 01:03:26,559
blank field that's offset from this

1593
01:03:30,390 --> 01:03:28,799
galaxy center and we take advantage of

1594
01:03:31,860 --> 01:03:30,400
this effect called

1595
01:03:33,270 --> 01:03:31,870
galaxy lensing

1596
01:03:35,430 --> 01:03:33,280
[Music]

1597
01:03:37,990 --> 01:03:35,440
where we're able to spot ultra distant

1598
01:03:39,910 --> 01:03:38,000
galaxies that are a bit fainter

1599
01:03:42,230 --> 01:03:39,920
this is the data that we got so on the

1600
01:03:44,390 --> 01:03:42,240
left you can see the nearest image where

1601
01:03:46,789 --> 01:03:44,400
everything within the field of view

1602
01:03:49,589 --> 01:03:46,799
we get a spectrum and on the right we

1603
01:03:51,829 --> 01:03:49,599
see the neocam seven um

1604
01:03:53,750 --> 01:03:51,839
seven band image

1605
01:03:56,150 --> 01:03:53,760
compressed together so we have three

1606
01:03:57,990 --> 01:03:56,160
different images uh across wavelengths

1607
01:03:59,270 --> 01:03:58,000
which we've combined

1608
01:04:01,029 --> 01:03:59,280
here on the left

1609
01:04:04,309 --> 01:04:01,039
and then seven different bands for near

1610
01:04:08,150 --> 01:04:06,549
so with 13 hours of nearest we already

1611
01:04:09,829 --> 01:04:08,160
confirmed two of the most distant

1612
01:04:11,990 --> 01:04:09,839
galaxies that we

1613
01:04:14,150 --> 01:04:12,000
currently know of you can see this

1614
01:04:16,309 --> 01:04:14,160
characteristic lineman break once more

1615
01:04:18,309 --> 01:04:16,319
now it's not shown with imaging but it's

1616
01:04:19,990 --> 01:04:18,319
shown with spectra you can see these

1617
01:04:21,829 --> 01:04:20,000
spectra here at the top and then at the

1618
01:04:24,230 --> 01:04:21,839
bottom you see the 1d

1619
01:04:26,069 --> 01:04:24,240
spectrum and you clearly see that break

1620
01:04:28,630 --> 01:04:26,079
and that break once again tells you the

1621
01:04:31,029 --> 01:04:28,640
redshift or the distance to the galaxies

1622
01:04:32,630 --> 01:04:31,039
and at the same time we then did a first

1623
01:04:36,470 --> 01:04:32,640
search for the most distant galaxies we

1624
01:04:38,150 --> 01:04:36,480
could see and we found uh two um

1625
01:04:39,910 --> 01:04:38,160
these two here at the top well we found

1626
01:04:42,470 --> 01:04:39,920
five other ones which are the red shifts

1627
01:04:44,150 --> 01:04:42,480
of nine to ten and then these other two

1628
01:04:46,069 --> 01:04:44,160
which were red shifts greater than ten

1629
01:04:48,069 --> 01:04:46,079
or so and you can again clearly see this

1630
01:04:49,670 --> 01:04:48,079
break but crucially i'm highlighting

1631
01:04:51,750 --> 01:04:49,680
here the filters that overlapped with

1632
01:04:53,510 --> 01:04:51,760
hubble and if you look at this one on

1633
01:04:56,470 --> 01:04:53,520
the right you see if we image this with

1634
01:04:59,430 --> 01:04:56,480
hubble we wouldn't see anything

1635
01:05:01,190 --> 01:04:59,440
glass is not the only ers program which

1636
01:05:04,630 --> 01:05:01,200
was recently

1637
01:05:07,910 --> 01:05:04,640
taken the sears survey was also taken

1638
01:05:10,390 --> 01:05:07,920
recently again a multi-band survey with

1639
01:05:12,630 --> 01:05:10,400
the near cam instruments um

1640
01:05:15,270 --> 01:05:12,640
on board the james webb space telescope

1641
01:05:17,589 --> 01:05:15,280
over a field that was previously known

1642
01:05:19,589 --> 01:05:17,599
with uh hubble previously imaged with

1643
01:05:22,150 --> 01:05:19,599
hubble again this is seven different

1644
01:05:25,270 --> 01:05:22,160
bands and you can see the mosaic over

1645
01:05:26,950 --> 01:05:25,280
here uh plotted throughout the screen uh

1646
01:05:29,190 --> 01:05:26,960
and um

1647
01:05:29,990 --> 01:05:29,200
researchers including ourselves had a

1648
01:05:33,910 --> 01:05:30,000
look

1649
01:05:34,829 --> 01:05:33,920
most distant galaxies we could

1650
01:05:39,029 --> 01:05:34,839
and

1651
01:05:43,190 --> 01:05:39,039
uh collaborators uh or the pis of sears

1652
01:05:45,589 --> 01:05:43,200
found this galaxy at a redshift of 14.3

1653
01:05:47,910 --> 01:05:45,599
this instantly breaks the records that

1654
01:05:50,470 --> 01:05:47,920
we previously had at a redshift of 11 or

1655
01:05:53,270 --> 01:05:50,480
so you can see this dropout nature over

1656
01:05:56,230 --> 01:05:53,280
here the the imaging is represented as

1657
01:05:58,630 --> 01:05:56,240
the circles here and our best fit model

1658
01:06:00,309 --> 01:05:58,640
of the galaxy as these lines

1659
01:06:02,549 --> 01:06:00,319
and you can see that it appears fairly

1660
01:06:04,390 --> 01:06:02,559
convincing and then

1661
01:06:06,950 --> 01:06:04,400
only a few days later

1662
01:06:09,510 --> 01:06:06,960
uh another galaxy that apparently broke

1663
01:06:12,390 --> 01:06:09,520
the distance record again at a redshift

1664
01:06:14,710 --> 01:06:12,400
of 16.6 so we're only looking at a few

1665
01:06:16,309 --> 01:06:14,720
hundred million years after the big bang

1666
01:06:18,230 --> 01:06:16,319
now and again you can see that

1667
01:06:19,430 --> 01:06:18,240
characteristic break and drop out

1668
01:06:22,390 --> 01:06:19,440
feature

1669
01:06:24,950 --> 01:06:22,400
but are we do we expect so many uh

1670
01:06:27,270 --> 01:06:24,960
distant galaxies um

1671
01:06:29,510 --> 01:06:27,280
our theory suggests perhaps not so over

1672
01:06:32,710 --> 01:06:29,520
here uh on the y-axis you see the

1673
01:06:34,309 --> 01:06:32,720
density of sources on the x-axis you see

1674
01:06:36,549 --> 01:06:34,319
the redshift and as you can see as you

1675
01:06:39,270 --> 01:06:36,559
go to higher and higher redshift you get

1676
01:06:41,589 --> 01:06:39,280
less and less sources and over here our

1677
01:06:43,750 --> 01:06:41,599
most distant known sources with hubble

1678
01:06:45,349 --> 01:06:43,760
seem to end at a redshift of 10 or so

1679
01:06:47,589 --> 01:06:45,359
suggesting that there's not really much

1680
01:06:50,230 --> 01:06:47,599
but james webb is now pushing this

1681
01:06:53,510 --> 01:06:50,240
frontier out to redshifts 12 13 and

1682
01:06:56,870 --> 01:06:53,520
nearly 17 suggesting perhaps uh that

1683
01:07:00,230 --> 01:06:56,880
star formation actually started um

1684
01:07:02,710 --> 01:07:00,240
at earlier times and not at later times

1685
01:07:05,029 --> 01:07:02,720
however all of these need to be verified

1686
01:07:07,750 --> 01:07:05,039
with spectroscopy um

1687
01:07:09,990 --> 01:07:07,760
the they remain galaxy candidates for

1688
01:07:11,829 --> 01:07:10,000
the moment until we can confirm them

1689
01:07:15,510 --> 01:07:11,839
with spectroscopy

1690
01:07:17,910 --> 01:07:15,520
and so one such programs uh that will be

1691
01:07:20,390 --> 01:07:17,920
doing so is my own one with james webb

1692
01:07:23,270 --> 01:07:20,400
where we'll be targeting 10 distant

1693
01:07:25,670 --> 01:07:23,280
galaxies for about 25 hours with near

1694
01:07:27,910 --> 01:07:25,680
spec so we'll be getting spectra from

1695
01:07:30,549 --> 01:07:27,920
0.6 microns all the way out to five

1696
01:07:32,069 --> 01:07:30,559
microns and we'll be able to detect all

1697
01:07:34,069 --> 01:07:32,079
of these features that i showed you

1698
01:07:36,150 --> 01:07:34,079
before including these strong emission

1699
01:07:39,029 --> 01:07:36,160
lines in only about an hour of

1700
01:07:40,950 --> 01:07:39,039
observations this is the near spec setup

1701
01:07:42,950 --> 01:07:40,960
so the galaxies will be placed in here

1702
01:07:44,789 --> 01:07:42,960
where you can get a spectrum for each of

1703
01:07:46,630 --> 01:07:44,799
the little slits that are in these

1704
01:07:48,789 --> 01:07:46,640
quadrants and this is the sort of

1705
01:07:51,109 --> 01:07:48,799
spectrum that we expect to get the 2d at

1706
01:07:52,710 --> 01:07:51,119
the top and if you collapse that you get

1707
01:07:54,789 --> 01:07:52,720
this beautiful spectrum here with all

1708
01:07:57,430 --> 01:07:54,799
these features

1709
01:07:59,510 --> 01:07:57,440
so i think i'm going to end it uh over

1710
01:08:01,349 --> 01:07:59,520
here my main takeaway messages is that

1711
01:08:03,510 --> 01:08:01,359
the ground and space-based facilities

1712
01:08:05,270 --> 01:08:03,520
that we've had up until now have really

1713
01:08:07,430 --> 01:08:05,280
pushed the frontier of the early galaxy

1714
01:08:09,510 --> 01:08:07,440
evolution we've discovered objects all

1715
01:08:11,829 --> 01:08:09,520
the way out to a redshift of 11 or so

1716
01:08:14,150 --> 01:08:11,839
we've constrained their distances their

1717
01:08:16,309 --> 01:08:14,160
masses and their star formation rates

1718
01:08:18,149 --> 01:08:16,319
and whilst in theory we would expect

1719
01:08:19,590 --> 01:08:18,159
these galaxies to be very young and

1720
01:08:20,550 --> 01:08:19,600
pristine

1721
01:08:22,550 --> 01:08:20,560
and

1722
01:08:24,550 --> 01:08:22,560
largely invisible to

1723
01:08:27,269 --> 01:08:24,560
uv imaging and spectroscopy

1724
01:08:29,430 --> 01:08:27,279
analyses with keck and the vlt for

1725
01:08:31,910 --> 01:08:29,440
instance suggest that actually these

1726
01:08:33,990 --> 01:08:31,920
galaxies might be

1727
01:08:35,510 --> 01:08:34,000
might be more massive more dusty than

1728
01:08:37,430 --> 01:08:35,520
previously thought and also formed

1729
01:08:40,709 --> 01:08:37,440
earlier than previously thought and

1730
01:08:43,189 --> 01:08:40,719
lastly the arrival of james webb uh is

1731
01:08:45,910 --> 01:08:43,199
now offering unprecedented imaging and

1732
01:08:47,590 --> 01:08:45,920
spectroscopic capabilities um you know

1733
01:08:49,189 --> 01:08:47,600
showing us images and spectra and

1734
01:08:52,709 --> 01:08:49,199
information about galaxies that we could

1735
01:08:54,789 --> 01:08:52,719
have only dreamed of up until now um

1736
01:08:57,749 --> 01:08:54,799
so i'll end it there thank you for your

1737
01:09:04,470 --> 01:09:01,189
and thank you guido this is uh an

1738
01:09:07,430 --> 01:09:04,480
intense look at not only what we have uh

1739
01:09:09,669 --> 01:09:07,440
previously discovered about this but a

1740
01:09:11,829 --> 01:09:09,679
sneak peek at what we are currently

1741
01:09:12,950 --> 01:09:11,839
discovering about these very early

1742
01:09:13,990 --> 01:09:12,960
galaxies

1743
01:09:16,070 --> 01:09:14,000
uh

1744
01:09:17,749 --> 01:09:16,080
the idea that we could push to redshift

1745
01:09:22,070 --> 01:09:17,759
16.5

1746
01:09:25,110 --> 01:09:22,080
as a totally unprecedented uh

1747
01:09:26,789 --> 01:09:25,120
not something that uh i got in the that

1748
01:09:29,910 --> 01:09:26,799
idea was not anywhere near in my head

1749
01:09:32,789 --> 01:09:29,920
when we were doing my graduate work

1750
01:09:34,709 --> 01:09:32,799
well dec a few decades ago

1751
01:09:36,470 --> 01:09:34,719
so you must be pleased with the uh the

1752
01:09:37,349 --> 01:09:36,480
progress we're getting we're making

1753
01:09:40,390 --> 01:09:37,359
there

1754
01:09:43,110 --> 01:09:40,400
it's wonderful i think uh none of us

1755
01:09:45,189 --> 01:09:43,120
we all expected to be surprised in some

1756
01:09:46,709 --> 01:09:45,199
shape or form but i don't think anyone

1757
01:09:49,910 --> 01:09:46,719
expected to be

1758
01:09:52,470 --> 01:09:49,920
uh surprised to this extent or this

1759
01:09:54,630 --> 01:09:52,480
quickly uh we've only had james webb for

1760
01:09:56,950 --> 01:09:54,640
about you know a month and a half or so

1761
01:09:58,709 --> 01:09:56,960
nearly two months uh it's already broken

1762
01:10:01,189 --> 01:09:58,719
the distance record

1763
01:10:03,350 --> 01:10:01,199
several times and it's already revealing

1764
01:10:05,990 --> 01:10:03,360
you know the physics of these early

1765
01:10:07,669 --> 01:10:06,000
galaxies in exquisite detail that we

1766
01:10:09,350 --> 01:10:07,679
could have only or you know that people

1767
01:10:10,630 --> 01:10:09,360
have been dreaming about for 10 to 20

1768
01:10:13,270 --> 01:10:10,640
years

1769
01:10:15,510 --> 01:10:13,280
okay well one of our uh

1770
01:10:18,470 --> 01:10:15,520
viewers on youtube was wondering okay

1771
01:10:21,590 --> 01:10:18,480
well you said hubble had a limit around

1772
01:10:24,790 --> 01:10:21,600
10 11 that it could go out to

1773
01:10:29,189 --> 01:10:24,800
uh if there were galaxies beyond these

1774
01:10:31,990 --> 01:10:29,199
14 and 16 just how far could

1775
01:10:33,590 --> 01:10:32,000
webb go if uh if if

1776
01:10:36,709 --> 01:10:33,600
if there are galaxies to observe at

1777
01:10:38,870 --> 01:10:36,719
those redshifts can it get to 1820

1778
01:10:41,510 --> 01:10:38,880
where is it is there a limit

1779
01:10:44,149 --> 01:10:41,520
uh in three yeah it can it can get to

1780
01:10:46,470 --> 01:10:44,159
1820 in fact you know there are there

1781
01:10:49,189 --> 01:10:46,480
are some results out there who uh you

1782
01:10:51,830 --> 01:10:49,199
know are suggesting that there might be

1783
01:10:54,229 --> 01:10:51,840
a couple of galaxies out at redshift20

1784
01:10:56,709 --> 01:10:54,239
this has to be verified and and

1785
01:10:59,350 --> 01:10:56,719
peer-reviewed uh but there are people

1786
01:11:01,270 --> 01:10:59,360
looking out as far as redshifts of 20.

1787
01:11:03,510 --> 01:11:01,280
of course you've pointed out a really

1788
01:11:05,669 --> 01:11:03,520
valid point though i think which is you

1789
01:11:07,270 --> 01:11:05,679
know we don't know whether they even

1790
01:11:08,310 --> 01:11:07,280
exist so

1791
01:11:10,950 --> 01:11:08,320
um

1792
01:11:13,990 --> 01:11:10,960
our models are a little doubtful let's

1793
01:11:16,550 --> 01:11:14,000
say of finding galaxies that far out

1794
01:11:18,709 --> 01:11:16,560
but if they do exist then in theory

1795
01:11:20,390 --> 01:11:18,719
james webb should be able to

1796
01:11:22,390 --> 01:11:20,400
find them the only thing is that we

1797
01:11:23,750 --> 01:11:22,400
wouldn't be able to look for the most

1798
01:11:26,070 --> 01:11:23,760
we'd only be able to look for the

1799
01:11:29,270 --> 01:11:26,080
brightest such sources because the faint

1800
01:11:30,870 --> 01:11:29,280
ones would still be out of uh i think

1801
01:11:32,550 --> 01:11:30,880
james webb's capabilities we'd have to

1802
01:11:34,950 --> 01:11:32,560
be looking at the sky for a very very

1803
01:11:37,430 --> 01:11:34,960
long time right and that's another thing

1804
01:11:39,510 --> 01:11:37,440
to point out to folks is that you know

1805
01:11:42,070 --> 01:11:39,520
what are we calling galaxies here i mean

1806
01:11:45,350 --> 01:11:42,080
these are sort of proto galaxies right i

1807
01:11:47,189 --> 01:11:45,360
mean um what is the masses are they are

1808
01:11:49,110 --> 01:11:47,199
are we getting down to like you know 10

1809
01:11:51,590 --> 01:11:49,120
to the eighth solar masses

1810
01:11:52,310 --> 01:11:51,600
uh type type range or

1811
01:11:55,189 --> 01:11:52,320
what

1812
01:11:56,790 --> 01:11:55,199
how large uh because they're certainly

1813
01:11:59,189 --> 01:11:56,800
not the size that they're not milky way

1814
01:12:01,590 --> 01:11:59,199
size galaxies they're not even you know

1815
01:12:03,350 --> 01:12:01,600
um dwarf they're not even the large

1816
01:12:05,270 --> 01:12:03,360
dwarfs that we know of in the local

1817
01:12:06,550 --> 01:12:05,280
universe what masses are we really

1818
01:12:08,229 --> 01:12:06,560
looking at when we're talking about

1819
01:12:10,470 --> 01:12:08,239
these very very so that's something

1820
01:12:12,950 --> 01:12:10,480
where we're actually able to

1821
01:12:15,590 --> 01:12:12,960
look at now for more or less the first

1822
01:12:17,750 --> 01:12:15,600
time uh most of the mass of these

1823
01:12:19,590 --> 01:12:17,760
galaxies is contained within the rest

1824
01:12:20,790 --> 01:12:19,600
frame optical which up until now we

1825
01:12:23,030 --> 01:12:20,800
could only see

1826
01:12:24,870 --> 01:12:23,040
with two bands with spitzer but these

1827
01:12:27,430 --> 01:12:24,880
bands were heavily contaminated by

1828
01:12:30,470 --> 01:12:27,440
emission lines and and features which

1829
01:12:32,070 --> 01:12:30,480
skewed let's say our results with um

1830
01:12:33,189 --> 01:12:32,080
james webb were able to do this more

1831
01:12:34,390 --> 01:12:33,199
efficiently

1832
01:12:36,390 --> 01:12:34,400
and people are finding that these

1833
01:12:38,709 --> 01:12:36,400
galaxies are more massive than we

1834
01:12:41,030 --> 01:12:38,719
thought 10 to the 9 10 to the 10 even in

1835
01:12:42,950 --> 01:12:41,040
some cases really so we're getting into

1836
01:12:45,189 --> 01:12:42,960
a billion solar masses and that is just

1837
01:12:48,830 --> 01:12:45,199
in baryons or is that baryons and dark

1838
01:12:51,590 --> 01:12:48,840
matter that's uh just baryons that's

1839
01:12:53,350 --> 01:12:51,600
just um all right wait wait for the

1840
01:12:55,270 --> 01:12:53,360
audience baryons is the normal matter

1841
01:12:57,590 --> 01:12:55,280
the hydrogen and the helium and stuff

1842
01:12:59,990 --> 01:12:57,600
it's amongst cosmologists baryons is

1843
01:13:01,830 --> 01:13:00,000
just what we use as our code word for

1844
01:13:03,750 --> 01:13:01,840
for that sort of that sort of stuff

1845
01:13:06,630 --> 01:13:03,760
gotta make sure that our public audience

1846
01:13:09,430 --> 01:13:06,640
recognizes those those jargon words

1847
01:13:10,149 --> 01:13:09,440
yeah yeah absolutely um i mean you know

1848
01:13:12,070 --> 01:13:10,159
the

1849
01:13:13,590 --> 01:13:12,080
regular matter we can see with james

1850
01:13:15,270 --> 01:13:13,600
webb dark matter we would have to

1851
01:13:17,430 --> 01:13:15,280
constrain indirectly through

1852
01:13:18,870 --> 01:13:17,440
gravitational effects we can't see that

1853
01:13:21,350 --> 01:13:18,880
directly

1854
01:13:24,390 --> 01:13:21,360
and so here we're talking normal matter

1855
01:13:26,790 --> 01:13:24,400
let's say you know the stars and gas

1856
01:13:29,430 --> 01:13:26,800
and in some cases we seem to be seeing

1857
01:13:31,510 --> 01:13:29,440
galaxies that are more massive than

1858
01:13:33,990 --> 01:13:31,520
previously thought you know we already

1859
01:13:37,189 --> 01:13:34,000
looked at this a little bit with uh with

1860
01:13:38,709 --> 01:13:37,199
spitzer and alma this jd1 galaxy for

1861
01:13:40,310 --> 01:13:38,719
instance which is

1862
01:13:42,630 --> 01:13:40,320
supposed to be a lot older and a lot

1863
01:13:44,470 --> 01:13:42,640
more massive than previously thought but

1864
01:13:46,550 --> 01:13:44,480
james webb is really taking this to

1865
01:13:49,110 --> 01:13:46,560
another level the only

1866
01:13:52,310 --> 01:13:49,120
the only caveat i will add to this in

1867
01:13:53,750 --> 01:13:52,320
terms of these distant galaxies is we

1868
01:13:55,350 --> 01:13:53,760
know how to

1869
01:13:56,870 --> 01:13:55,360
um

1870
01:13:58,550 --> 01:13:56,880
we know how to search for distant

1871
01:14:01,189 --> 01:13:58,560
galaxies and characterize them

1872
01:14:04,149 --> 01:14:01,199
reasonably well what we don't know very

1873
01:14:07,110 --> 01:14:04,159
well yet is the uh is how the

1874
01:14:09,910 --> 01:14:07,120
instruments of james webb behave and so

1875
01:14:12,870 --> 01:14:09,920
a very important uh component of all of

1876
01:14:15,350 --> 01:14:12,880
this is essentially learning on the fly

1877
01:14:16,950 --> 01:14:15,360
how these instruments respond and making

1878
01:14:19,510 --> 01:14:16,960
sure that they respond in a way that we

1879
01:14:21,590 --> 01:14:19,520
understand and so what we then interpret

1880
01:14:23,350 --> 01:14:21,600
of these galaxies is accurate and that

1881
01:14:25,430 --> 01:14:23,360
will take a little bit of time still

1882
01:14:27,270 --> 01:14:25,440
exactly experience i mean

1883
01:14:28,709 --> 01:14:27,280
i remember several times in hubble's

1884
01:14:30,550 --> 01:14:28,719
history that we've had to recalibrate

1885
01:14:32,630 --> 01:14:30,560
all go back through and you know do

1886
01:14:34,709 --> 01:14:32,640
recalibrations of the all the data sets

1887
01:14:37,270 --> 01:14:34,719
in the archive just because we've

1888
01:14:39,430 --> 01:14:37,280
learned more about how uh how the

1889
01:14:40,149 --> 01:14:39,440
instruments are are responding

1890
01:14:42,870 --> 01:14:40,159
so

1891
01:14:45,910 --> 01:14:42,880
even if we have fantastic observations

1892
01:14:47,110 --> 01:14:45,920
of fantastic results right now

1893
01:14:48,390 --> 01:14:47,120
they all they have to be taken with a

1894
01:14:51,350 --> 01:14:48,400
grain of salt until we have the

1895
01:14:53,750 --> 01:14:51,360
experience with webb's instruments uh to

1896
01:14:56,870 --> 01:14:53,760
really validate them

1897
01:14:59,590 --> 01:14:56,880
that's right but part of part of uh

1898
01:15:00,550 --> 01:14:59,600
the excitement of james webb is also

1899
01:15:06,310 --> 01:15:00,560
you know

1900
01:15:07,990 --> 01:15:06,320
we expect we expect our results to be

1901
01:15:10,709 --> 01:15:08,000
extended to a certain extent we always

1902
01:15:11,750 --> 01:15:10,719
expect to find more distant galaxies i

1903
01:15:13,430 --> 01:15:11,760
think but

1904
01:15:15,990 --> 01:15:13,440
part of the enjoyment of all of this is

1905
01:15:18,229 --> 01:15:16,000
really being surprised in in ways which

1906
01:15:21,430 --> 01:15:18,239
we didn't really imagine

1907
01:15:23,110 --> 01:15:21,440
and that forces us then to

1908
01:15:25,270 --> 01:15:23,120
rethink you know perhaps some of our

1909
01:15:26,950 --> 01:15:25,280
models or our techniques and uh rethink

1910
01:15:29,110 --> 01:15:26,960
what we know and that's a wonderful part

1911
01:15:30,149 --> 01:15:29,120
of astronomy and science in general i

1912
01:15:32,310 --> 01:15:30,159
think

1913
01:15:34,550 --> 01:15:32,320
wonderful yeah i will definitely say

1914
01:15:35,990 --> 01:15:34,560
that you know 14 and 16 right in the

1915
01:15:38,229 --> 01:15:36,000
first month is

1916
01:15:39,830 --> 01:15:38,239
definitely qualify as a surprise all

1917
01:15:41,830 --> 01:15:39,840
right there was one other question i saw

1918
01:15:43,430 --> 01:15:41,840
that i wanted to ask you um

1919
01:15:46,310 --> 01:15:43,440
and it's trying to relate the local

1920
01:15:48,229 --> 01:15:46,320
universe to the distant universe and so

1921
01:15:50,229 --> 01:15:48,239
they asked a question that i translated

1922
01:15:52,630 --> 01:15:50,239
into two different questions one

1923
01:15:55,350 --> 01:15:52,640
are galaxies being formed today

1924
01:15:58,149 --> 01:15:55,360
um and are they similar to these very

1925
01:15:59,750 --> 01:15:58,159
early galaxies i presume sort of saying

1926
01:16:01,430 --> 01:15:59,760
hey if what

1927
01:16:03,030 --> 01:16:01,440
what is what we see in the local

1928
01:16:04,950 --> 01:16:03,040
universe similar to what we're seeing in

1929
01:16:08,149 --> 01:16:04,960
the distant universe just at much much

1930
01:16:15,189 --> 01:16:12,630
uh that's that's a very good question um

1931
01:16:17,830 --> 01:16:15,199
yes is the answer we have

1932
01:16:20,790 --> 01:16:17,840
uh so there are galaxies forming forming

1933
01:16:23,750 --> 01:16:20,800
today uh and there are galaxies also

1934
01:16:25,189 --> 01:16:23,760
that uh look very similar to

1935
01:16:27,270 --> 01:16:25,199
um

1936
01:16:29,830 --> 01:16:27,280
to what we see in the distance distant

1937
01:16:32,149 --> 01:16:29,840
universe obviously everything we look at

1938
01:16:34,709 --> 01:16:32,159
is you know a snapshot of the past in a

1939
01:16:37,910 --> 01:16:34,719
way we can't see this in real time but

1940
01:16:39,750 --> 01:16:37,920
this is actually a very big part of um

1941
01:16:42,470 --> 01:16:39,760
studies of the early universe because

1942
01:16:45,590 --> 01:16:42,480
these faraway galaxies are so difficult

1943
01:16:47,270 --> 01:16:45,600
to find and confirm we often look at the

1944
01:16:49,590 --> 01:16:47,280
local universe

1945
01:16:51,750 --> 01:16:49,600
looking for what we call uh lower

1946
01:16:53,910 --> 01:16:51,760
redshift analogues of high wretched

1947
01:16:56,390 --> 01:16:53,920
galaxies so galaxies in the local

1948
01:16:58,709 --> 01:16:56,400
universe that we think resemble very

1949
01:17:00,630 --> 01:16:58,719
distant galaxies to try and understand

1950
01:17:03,669 --> 01:17:00,640
more about the properties and conditions

1951
01:17:06,310 --> 01:17:03,679
of those galaxies so yes and yes is the

1952
01:17:09,030 --> 01:17:06,320
answer to that i think and i guess i

1953
01:17:11,189 --> 01:17:09,040
would think that there is a significant

1954
01:17:12,790 --> 01:17:11,199
difference between them in that these

1955
01:17:14,630 --> 01:17:12,800
galaxies we're seeing in the very early

1956
01:17:16,149 --> 01:17:14,640
universe you know if they're forming so

1957
01:17:18,070 --> 01:17:16,159
quickly they're going to continue to

1958
01:17:20,470 --> 01:17:18,080
form and and probably end up as you know

1959
01:17:22,070 --> 01:17:20,480
giant elliptical galaxies whereas the

1960
01:17:23,750 --> 01:17:22,080
ones in the local universe are going to

1961
01:17:25,590 --> 01:17:23,760
be these dwarf small galaxies and

1962
01:17:27,270 --> 01:17:25,600
they're never going to get to be the

1963
01:17:29,110 --> 01:17:27,280
giant ellipticals i mean the things that

1964
01:17:32,709 --> 01:17:29,120
don't form first are the highest density

1965
01:17:34,709 --> 01:17:32,719
peaks of the density distribution so

1966
01:17:36,870 --> 01:17:34,719
there's that small difference i've

1967
01:17:38,790 --> 01:17:36,880
always kept in my head is that

1968
01:17:40,310 --> 01:17:38,800
reasonable

1969
01:17:42,870 --> 01:17:40,320
yeah i think that sounds that's

1970
01:17:45,189 --> 01:17:42,880
definitely reasonable obviously we don't

1971
01:17:47,830 --> 01:17:45,199
in our lifetimes we won't know how these

1972
01:17:50,790 --> 01:17:47,840
currently forming galaxies are going to

1973
01:17:52,149 --> 01:17:50,800
going to evolve but i think one one

1974
01:17:54,310 --> 01:17:52,159
thing that's important to consider of

1975
01:17:56,149 --> 01:17:54,320
course when doing these studies is uh

1976
01:17:58,390 --> 01:17:56,159
you know it is very well and good to

1977
01:18:01,110 --> 01:17:58,400
compare these galaxies across across

1978
01:18:02,950 --> 01:18:01,120
cosmic time but we should keep in mind

1979
01:18:05,669 --> 01:18:02,960
that the conditions of the universe have

1980
01:18:07,189 --> 01:18:05,679
changed you know across 13 billion years

1981
01:18:09,990 --> 01:18:07,199
so the conditions in which the first

1982
01:18:12,550 --> 01:18:10,000
galaxies form are different to the

1983
01:18:15,030 --> 01:18:12,560
conditions in which the galaxies today

1984
01:18:17,189 --> 01:18:15,040
are forming uh nonetheless you know if

1985
01:18:19,350 --> 01:18:17,199
you compare apples to apples in terms of

1986
01:18:20,149 --> 01:18:19,360
specific properties that i think one can

1987
01:18:22,550 --> 01:18:20,159
do

1988
01:18:24,870 --> 01:18:22,560
but for sure uh the conditions around

1989
01:18:27,350 --> 01:18:24,880
those galaxies has changed and no doubt

1990
01:18:29,110 --> 01:18:27,360
that would have some sort of impact uh

1991
01:18:31,910 --> 01:18:29,120
on the structure the large-scale

1992
01:18:34,149 --> 01:18:31,920
structures of galaxies at least right

1993
01:18:37,030 --> 01:18:34,159
okay well grant justice has been paying

1994
01:18:39,110 --> 01:18:37,040
attention to the questions in the chat

1995
01:18:41,750 --> 01:18:39,120
grant why don't you turn on your video

1996
01:18:44,070 --> 01:18:41,760
and uh welcome and tell us what

1997
01:18:46,229 --> 01:18:44,080
questions you found in in the chat

1998
01:18:48,630 --> 01:18:46,239
sure absolutely actually following up

1999
01:18:51,750 --> 01:18:48,640
kind of from the last one uh in your

2000
01:18:54,870 --> 01:18:51,760
observations have you found that

2001
01:18:57,270 --> 01:18:54,880
uh early galaxies tend to have

2002
01:18:59,510 --> 01:18:57,280
uh larger or smaller

2003
01:19:02,950 --> 01:18:59,520
stars compared to recently formed one is

2004
01:19:08,310 --> 01:19:05,270
so we don't have we don't have the

2005
01:19:11,830 --> 01:19:08,320
resolution to look at individual stars

2006
01:19:14,550 --> 01:19:11,840
in these distant galaxies

2007
01:19:17,430 --> 01:19:14,560
galaxies that are closer by we can see

2008
01:19:19,030 --> 01:19:17,440
clusters of of galaxies but we don't

2009
01:19:21,830 --> 01:19:19,040
quite have the resolution to look at

2010
01:19:25,430 --> 01:19:21,840
stars individual stars outside of our

2011
01:19:27,430 --> 01:19:25,440
own galaxy what we can do though is

2012
01:19:29,030 --> 01:19:27,440
we can compare the sizes of galaxies

2013
01:19:31,750 --> 01:19:29,040
themselves or we can try and estimate

2014
01:19:34,390 --> 01:19:31,760
the ages of the stars within and we do

2015
01:19:35,270 --> 01:19:34,400
find that some of these distant galaxies

2016
01:19:37,750 --> 01:19:35,280
have

2017
01:19:39,750 --> 01:19:37,760
older stars the stars that we see today

2018
01:19:41,669 --> 01:19:39,760
are much much older because

2019
01:19:44,950 --> 01:19:41,679
galaxies have had a lot more time to

2020
01:19:47,030 --> 01:19:44,960
evolve uh than those early ones um but

2021
01:19:50,070 --> 01:19:47,040
if you compare for instance with these

2022
01:19:52,229 --> 01:19:50,080
so-called local analogs then we see

2023
01:19:53,669 --> 01:19:52,239
we can see some similar traits across

2024
01:19:55,669 --> 01:19:53,679
the two different populations but we

2025
01:19:58,390 --> 01:19:55,679
can't we don't have the resolution even

2026
01:20:00,870 --> 01:19:58,400
with james webb to uh image individual

2027
01:20:02,790 --> 01:20:00,880
stars in these distant galaxies okay so

2028
01:20:05,030 --> 01:20:02,800
that brings up a side question that you

2029
01:20:07,270 --> 01:20:05,040
mentioned a bit in your talk that we got

2030
01:20:09,110 --> 01:20:07,280
the redshift for a galaxy to know

2031
01:20:10,709 --> 01:20:09,120
what redshift we're seeing it at and

2032
01:20:12,550 --> 01:20:10,719
then we can age date you know that

2033
01:20:14,709 --> 01:20:12,560
you've got some stars within them that

2034
01:20:15,430 --> 01:20:14,719
are like a few hundred million years old

2035
01:20:17,910 --> 01:20:15,440
so

2036
01:20:19,830 --> 01:20:17,920
are we getting a good estimate for when

2037
01:20:22,229 --> 01:20:19,840
this first stars in in the universe

2038
01:20:24,070 --> 01:20:22,239
formed how how close to the big bang

2039
01:20:26,870 --> 01:20:24,080
we're getting there

2040
01:20:28,790 --> 01:20:26,880
that that's an excellent question so

2041
01:20:30,870 --> 01:20:28,800
when we get the light from the galaxies

2042
01:20:33,430 --> 01:20:30,880
we're seeing them as they were then and

2043
01:20:36,310 --> 01:20:33,440
if we can measure the age of those stars

2044
01:20:38,470 --> 01:20:36,320
then what we can do is rewind the clock

2045
01:20:41,910 --> 01:20:38,480
the way we do this essentially is we

2046
01:20:44,149 --> 01:20:41,920
recreate the history of how this galaxy

2047
01:20:46,629 --> 01:20:44,159
formed those stars by trying to match

2048
01:20:48,790 --> 01:20:46,639
the light profile but this is and we do

2049
01:20:52,310 --> 01:20:48,800
this with models of galaxies but this is

2050
01:20:54,390 --> 01:20:52,320
an extremely uncertain uh practice it's

2051
01:20:57,030 --> 01:20:54,400
the only way we can do things for the

2052
01:20:57,910 --> 01:20:57,040
moment in the absence of spectroscopy

2053
01:21:00,310 --> 01:20:57,920
um

2054
01:21:02,390 --> 01:21:00,320
it was the only way to do it so you can

2055
01:21:05,830 --> 01:21:02,400
pinpoint then a

2056
01:21:08,470 --> 01:21:05,840
um a time at which these galaxies uh

2057
01:21:10,229 --> 01:21:08,480
were born or these stars were born but

2058
01:21:12,390 --> 01:21:10,239
it'll still have a very large error bar

2059
01:21:15,350 --> 01:21:12,400
it's very uncertain what you need is

2060
01:21:17,510 --> 01:21:15,360
spectroscopy to be able to look at this

2061
01:21:19,510 --> 01:21:17,520
so-called bomber break again this jump

2062
01:21:21,590 --> 01:21:19,520
that you see which is due to those

2063
01:21:23,750 --> 01:21:21,600
mature stars and if you can directly

2064
01:21:26,070 --> 01:21:23,760
measure that jump you'll have a much

2065
01:21:28,390 --> 01:21:26,080
better handle on the ages of those stars

2066
01:21:31,189 --> 01:21:28,400
than just from imaging alone

2067
01:21:33,270 --> 01:21:31,199
okay but it does sound like we're

2068
01:21:35,830 --> 01:21:33,280
finding that you know the first stars

2069
01:21:38,149 --> 01:21:35,840
are forming uh within 500 million years

2070
01:21:39,750 --> 01:21:38,159
after the big bang yeah yeah so we're

2071
01:21:41,350 --> 01:21:39,760
getting getting it exact it's going to

2072
01:21:43,110 --> 01:21:41,360
be

2073
01:21:45,350 --> 01:21:43,120
something to look forward to

2074
01:21:47,350 --> 01:21:45,360
that's right that's right um

2075
01:21:50,149 --> 01:21:47,360
we know gen we know at this point in

2076
01:21:52,390 --> 01:21:50,159
time now just due to distances alone i

2077
01:21:54,709 --> 01:21:52,400
mean confirming distances to early

2078
01:21:56,229 --> 01:21:54,719
galaxies the most direct way to

2079
01:21:58,629 --> 01:21:56,239
essentially figure out when the first

2080
01:22:00,790 --> 01:21:58,639
stars and galaxies formed and that alone

2081
01:22:02,470 --> 01:22:00,800
is telling us that the first stars and

2082
01:22:03,590 --> 01:22:02,480
galaxies probably formed within the

2083
01:22:05,830 --> 01:22:03,600
first

2084
01:22:07,270 --> 01:22:05,840
two to 400 million years after the big

2085
01:22:10,550 --> 01:22:07,280
bang or so

2086
01:22:12,709 --> 01:22:10,560
roughly 96 97 percent of the universe's

2087
01:22:13,910 --> 01:22:12,719
present age

2088
01:22:15,510 --> 01:22:13,920
all right

2089
01:22:17,990 --> 01:22:15,520
okay else we got

2090
01:22:21,910 --> 01:22:18,000
i i actually love this one we're gonna

2091
01:22:24,550 --> 01:22:21,920
pull back the the curtain a little bit

2092
01:22:26,709 --> 01:22:24,560
is it common to incorrectly date such

2093
01:22:28,310 --> 01:22:26,719
early distant galaxies

2094
01:22:32,390 --> 01:22:28,320
it's nothing short of incredible that

2095
01:22:37,270 --> 01:22:35,030
that's a great question the answer is

2096
01:22:39,510 --> 01:22:37,280
the answer is probably but we don't know

2097
01:22:41,110 --> 01:22:39,520
until we actually confirm

2098
01:22:43,990 --> 01:22:41,120
those you know the dates of these

2099
01:22:46,709 --> 01:22:44,000
galaxies um there's there's a very large

2100
01:22:48,870 --> 01:22:46,719
error bar on these estimates so whether

2101
01:22:51,750 --> 01:22:48,880
we've pinpointed the exact age or not

2102
01:22:54,390 --> 01:22:51,760
remains to be seen but there's a very

2103
01:22:56,950 --> 01:22:54,400
gray area there let's say um

2104
01:22:59,910 --> 01:22:56,960
you know a big margin ferreira um yeah

2105
01:23:01,750 --> 01:22:59,920
but so don't sell yourself short because

2106
01:23:03,910 --> 01:23:01,760
error bars have been decreasing from

2107
01:23:05,590 --> 01:23:03,920
being really huge now you know you're

2108
01:23:07,270 --> 01:23:05,600
just saying okay earth they're here and

2109
01:23:10,229 --> 01:23:07,280
they should they really want them to be

2110
01:23:12,629 --> 01:23:10,239
here but you're doing fantastic

2111
01:23:14,709 --> 01:23:12,639
absolutely thank you i mean uh you know

2112
01:23:16,790 --> 01:23:14,719
these telescopes really are allowing us

2113
01:23:19,110 --> 01:23:16,800
to push the frontier of what we can do i

2114
01:23:20,390 --> 01:23:19,120
mean it is it is marvelous that we're

2115
01:23:23,110 --> 01:23:20,400
even able to

2116
01:23:25,270 --> 01:23:23,120
attempt this sort of thing um but

2117
01:23:27,830 --> 01:23:25,280
ultimately getting sort of direct

2118
01:23:29,430 --> 01:23:27,840
confirmation is what we want to do uh

2119
01:23:31,110 --> 01:23:29,440
but that's extremely challenging one of

2120
01:23:33,510 --> 01:23:31,120
the things that you know people have

2121
01:23:35,430 --> 01:23:33,520
been wanting to do for a long time is is

2122
01:23:38,229 --> 01:23:35,440
the detection confirmation of what we

2123
01:23:40,950 --> 01:23:38,239
call population three stars these these

2124
01:23:42,790 --> 01:23:40,960
first generation of stars uh they're the

2125
01:23:45,910 --> 01:23:42,800
very first ones that formed from

2126
01:23:48,229 --> 01:23:45,920
pristine hydrogen gas they don't have

2127
01:23:49,110 --> 01:23:48,239
any heavy metals like carbon or oxygen

2128
01:23:51,110 --> 01:23:49,120
in them

2129
01:23:53,030 --> 01:23:51,120
and those are the ones that we know with

2130
01:23:54,629 --> 01:23:53,040
the very first ones to form and direct

2131
01:23:57,030 --> 01:23:54,639
detection is much

2132
01:23:59,110 --> 01:23:57,040
clearer let's say than rewinding the

2133
01:24:01,350 --> 01:23:59,120
clock as such but for the moment it's

2134
01:24:03,510 --> 01:24:01,360
the only thing we really can do

2135
01:24:05,990 --> 01:24:03,520
right and for those pop three stars it's

2136
01:24:07,830 --> 01:24:06,000
uh you know i've seen different

2137
01:24:11,110 --> 01:24:07,840
arguments as to how quickly those might

2138
01:24:12,629 --> 01:24:11,120
form um uh once the after after

2139
01:24:14,229 --> 01:24:12,639
re-ionization

2140
01:24:16,790 --> 01:24:14,239
that's right

2141
01:24:20,550 --> 01:24:16,800
recombination sorry

2142
01:24:23,590 --> 01:24:20,560
okay grant what next thank you um yeah

2143
01:24:26,070 --> 01:24:23,600
do indications of dust in these deeply

2144
01:24:30,149 --> 01:24:26,080
redshifted galaxies upset prediction

2145
01:24:34,229 --> 01:24:30,159
models of early star formation

2146
01:24:37,270 --> 01:24:34,239
again a good good question uh

2147
01:24:39,350 --> 01:24:37,280
yes to a certain extent for a very long

2148
01:24:41,110 --> 01:24:39,360
time uh the assumption with these

2149
01:24:43,430 --> 01:24:41,120
galaxies was that they didn't have any

2150
01:24:45,990 --> 01:24:43,440
dust at all in fact in a lot of our

2151
01:24:47,350 --> 01:24:46,000
analyses and our models dust was never

2152
01:24:50,870 --> 01:24:47,360
included

2153
01:24:53,350 --> 01:24:50,880
which has a significant impact on how we

2154
01:24:56,390 --> 01:24:53,360
interpret the data because dust in

2155
01:24:58,550 --> 01:24:56,400
effect shields uh a lot of the light

2156
01:24:59,910 --> 01:24:58,560
from young stars so for instance if

2157
01:25:02,310 --> 01:24:59,920
there's a lot of dust in these young

2158
01:25:03,910 --> 01:25:02,320
galaxies we might be under counting the

2159
01:25:05,510 --> 01:25:03,920
number of stars that they're forming and

2160
01:25:08,870 --> 01:25:05,520
that's really important for our models

2161
01:25:10,950 --> 01:25:08,880
of early galaxy evolution

2162
01:25:13,110 --> 01:25:10,960
so we hadn't been including that because

2163
01:25:16,070 --> 01:25:13,120
we assumed there was no stars

2164
01:25:19,270 --> 01:25:16,080
there was no dust sorry alma has really

2165
01:25:20,870 --> 01:25:19,280
been revolutionizing uh this picture uh

2166
01:25:22,550 --> 01:25:20,880
in the sense that it's an extremely

2167
01:25:24,390 --> 01:25:22,560
sensitive telescope in the sub

2168
01:25:26,870 --> 01:25:24,400
millimeter uh

2169
01:25:30,070 --> 01:25:26,880
range of wavelengths and that is where

2170
01:25:32,229 --> 01:25:30,080
galaxies tend to emit light from dust so

2171
01:25:34,070 --> 01:25:32,239
the dust gets heated up it absorbs uv

2172
01:25:35,910 --> 01:25:34,080
light and then re-emits it at infrared

2173
01:25:38,470 --> 01:25:35,920
wavelengths or sub-millimeter

2174
01:25:40,550 --> 01:25:38,480
wavelengths rather uh and alma is

2175
01:25:42,790 --> 01:25:40,560
finding in these very distant galaxies

2176
01:25:44,229 --> 01:25:42,800
that there seems to be a fair amount of

2177
01:25:46,229 --> 01:25:44,239
dust and so

2178
01:25:48,310 --> 01:25:46,239
what we need to do now is look back on

2179
01:25:50,149 --> 01:25:48,320
our theory on how this dust is produced

2180
01:25:52,070 --> 01:25:50,159
in terms of supernovae

2181
01:25:54,070 --> 01:25:52,080
or not and whether supernovae come from

2182
01:25:56,070 --> 01:25:54,080
these massive stars or not so yes it is

2183
01:25:58,470 --> 01:25:56,080
upsetting a little bit let's say our

2184
01:26:00,629 --> 01:25:58,480
original theories but that's great it

2185
01:26:02,709 --> 01:26:00,639
means we still have a lot to learn

2186
01:26:04,310 --> 01:26:02,719
yes i always like to say when you

2187
01:26:05,990 --> 01:26:04,320
uncover something you didn't expect it

2188
01:26:08,149 --> 01:26:06,000
just shows you you've got another

2189
01:26:10,790 --> 01:26:08,159
another project to pursue to understand

2190
01:26:13,270 --> 01:26:10,800
that result and um we love being

2191
01:26:15,590 --> 01:26:13,280
ignorant because that gives us more to

2192
01:26:18,149 --> 01:26:15,600
to understand about the universe

2193
01:26:21,189 --> 01:26:19,110
right

2194
01:26:23,430 --> 01:26:21,199
um so

2195
01:26:26,470 --> 01:26:23,440
given that you have so much more

2196
01:26:27,669 --> 01:26:26,480
available to you coming up now with jwst

2197
01:26:29,830 --> 01:26:27,679
we've spoken a little bit about the

2198
01:26:31,270 --> 01:26:29,840
instruments and like becoming familiar

2199
01:26:33,030 --> 01:26:31,280
with them but

2200
01:26:35,990 --> 01:26:33,040
what are you most excited for like

2201
01:26:38,390 --> 01:26:36,000
technique wise for dating early objects

2202
01:26:41,830 --> 01:26:38,400
or exploring a little further into your

2203
01:26:43,350 --> 01:26:41,840
speed like your specialty

2204
01:26:45,590 --> 01:26:43,360
that might be my favorite question i

2205
01:26:47,590 --> 01:26:45,600
think so far purely because

2206
01:26:49,590 --> 01:26:47,600
i think

2207
01:26:51,830 --> 01:26:49,600
what

2208
01:26:54,310 --> 01:26:51,840
the nice thing about james webb now and

2209
01:26:56,470 --> 01:26:54,320
having these capabilities which we could

2210
01:27:00,709 --> 01:26:56,480
only dream about

2211
01:27:02,950 --> 01:27:00,719
for a long time is it's no longer

2212
01:27:05,189 --> 01:27:02,960
the frontier is no longer just extending

2213
01:27:06,229 --> 01:27:05,199
what we've done so far the frontier now

2214
01:27:08,629 --> 01:27:06,239
i think

2215
01:27:11,430 --> 01:27:08,639
is becoming creative with

2216
01:27:14,070 --> 01:27:11,440
the capabilities that we've that we have

2217
01:27:15,669 --> 01:27:14,080
and learning how to combine the

2218
01:27:18,229 --> 01:27:15,679
instrument the data from these various

2219
01:27:20,229 --> 01:27:18,239
instruments uh in terms of trying to

2220
01:27:22,709 --> 01:27:20,239
understand what we see and where we

2221
01:27:24,310 --> 01:27:22,719
combine you know these different uh

2222
01:27:26,709 --> 01:27:24,320
indicators for instance what does that

2223
01:27:28,870 --> 01:27:26,719
tell us about galaxy evolution so it's

2224
01:27:30,950 --> 01:27:28,880
the unexpected let's say and and the

2225
01:27:32,870 --> 01:27:30,960
unknown which i think is really

2226
01:27:35,910 --> 01:27:32,880
interesting and i think the challenge

2227
01:27:37,510 --> 01:27:35,920
really now is to get creative uh with

2228
01:27:38,950 --> 01:27:37,520
the instruments and the data sets and

2229
01:27:41,669 --> 01:27:38,960
this is something that we're trying to

2230
01:27:43,830 --> 01:27:41,679
do with the glass crs program in terms

2231
01:27:45,910 --> 01:27:43,840
of uh you know looking at this galaxy

2232
01:27:47,910 --> 01:27:45,920
cluster not just with the nearest

2233
01:27:50,070 --> 01:27:47,920
instrument which is going to give us

2234
01:27:51,990 --> 01:27:50,080
which has given us a spectra of

2235
01:27:53,669 --> 01:27:52,000
everything in the field of view but also

2236
01:27:55,189 --> 01:27:53,679
then following it up at different

2237
01:27:56,709 --> 01:27:55,199
wavelengths with the near spec

2238
01:27:58,950 --> 01:27:56,719
instrument so that we can directly

2239
01:28:00,470 --> 01:27:58,960
compare different wavelengths and just

2240
01:28:03,270 --> 01:28:00,480
different instruments and see how to

2241
01:28:05,830 --> 01:28:03,280
best optimize them to learn as much as

2242
01:28:07,910 --> 01:28:05,840
we can about these distant objects

2243
01:28:10,229 --> 01:28:07,920
yeah and you had a great point about

2244
01:28:12,629 --> 01:28:10,239
using observations with alma

2245
01:28:14,629 --> 01:28:12,639
right and getting into the millimeter

2246
01:28:16,709 --> 01:28:14,639
and the radio waves which have

2247
01:28:18,470 --> 01:28:16,719
very fine resolution as well

2248
01:28:20,709 --> 01:28:18,480
um you know

2249
01:28:23,510 --> 01:28:20,719
uh hubble and webb are the kings of the

2250
01:28:25,910 --> 01:28:23,520
sky of the or uh the space telescopes

2251
01:28:27,590 --> 01:28:25,920
and getting the resolution but uh going

2252
01:28:29,590 --> 01:28:27,600
to the uh

2253
01:28:31,350 --> 01:28:29,600
millimeter and radio wavelengths where

2254
01:28:33,590 --> 01:28:31,360
you can get these big arrays to have the

2255
01:28:35,189 --> 01:28:33,600
really fine resolution um i'm sure

2256
01:28:36,790 --> 01:28:35,199
you'll be able to figure out some cool

2257
01:28:40,070 --> 01:28:36,800
ways to involve them

2258
01:28:42,149 --> 01:28:40,080
into adding more to the the information

2259
01:28:43,990 --> 01:28:42,159
uh that you get to sort and to find out

2260
01:28:46,070 --> 01:28:44,000
the input absolutely

2261
01:28:48,790 --> 01:28:46,080
so there's already you know this this

2262
01:28:50,550 --> 01:28:48,800
james webb alma synergy is something

2263
01:28:52,229 --> 01:28:50,560
that everybody is really looking forward

2264
01:28:55,110 --> 01:28:52,239
to because alma

2265
01:28:57,510 --> 01:28:55,120
probes physical mechanisms and you know

2266
01:29:00,709 --> 01:28:57,520
frequencies or wavelengths that james

2267
01:29:02,790 --> 01:29:00,719
webb does not probe and so you know one

2268
01:29:05,830 --> 01:29:02,800
example for instance of how

2269
01:29:08,629 --> 01:29:05,840
two examples let's say of how we want to

2270
01:29:11,030 --> 01:29:08,639
use this synergy is uh let's say the

2271
01:29:13,350 --> 01:29:11,040
confirmation for instance of

2272
01:29:15,910 --> 01:29:13,360
redshifts or distances you know as an

2273
01:29:18,629 --> 01:29:15,920
example if we if we get a so-called

2274
01:29:21,189 --> 01:29:18,639
dropout galaxy like i showed with james

2275
01:29:23,990 --> 01:29:21,199
webb which does not show we we do not

2276
01:29:25,750 --> 01:29:24,000
have spectroscopy for that one avenue is

2277
01:29:27,750 --> 01:29:25,760
possibly we can try and get a spectrum

2278
01:29:29,270 --> 01:29:27,760
of lyman alpha which might not show

2279
01:29:31,510 --> 01:29:29,280
because it might be

2280
01:29:33,990 --> 01:29:31,520
absorbed by the intervening hydrogen at

2281
01:29:36,390 --> 01:29:34,000
that epoch so we might look for emission

2282
01:29:38,229 --> 01:29:36,400
lines with alma which looks for oxygen

2283
01:29:40,950 --> 01:29:38,239
traces for instance like i had shown

2284
01:29:42,950 --> 01:29:40,960
before and that oxygen is not

2285
01:29:44,470 --> 01:29:42,960
affected by the surrounding medium of

2286
01:29:47,669 --> 01:29:44,480
those galaxies so

2287
01:29:50,149 --> 01:29:47,679
james webb would would find these

2288
01:29:53,189 --> 01:29:50,159
distant candidates alma might confirm

2289
01:29:56,390 --> 01:29:53,199
another one again is dust uh you know um

2290
01:29:59,910 --> 01:29:56,400
alma really probes uh the dusts that

2291
01:30:01,669 --> 01:29:59,920
james webb cannot and so trying to um

2292
01:30:03,430 --> 01:30:01,679
maximize the synergy between the two

2293
01:30:05,669 --> 01:30:03,440
telescopes to try and understand where

2294
01:30:06,550 --> 01:30:05,679
this dust is coming from and how much is

2295
01:30:08,870 --> 01:30:06,560
there

2296
01:30:09,830 --> 01:30:08,880
is really really important

2297
01:30:11,830 --> 01:30:09,840
all right

2298
01:30:14,229 --> 01:30:11,840
i think we're gonna let you have one

2299
01:30:16,390 --> 01:30:14,239
more question so grant uh find a good

2300
01:30:17,669 --> 01:30:16,400
one to end with here

2301
01:30:20,149 --> 01:30:17,679
because all right

2302
01:30:21,430 --> 01:30:20,159
we've gone on long enough here

2303
01:30:24,070 --> 01:30:21,440
that's fair

2304
01:30:26,709 --> 01:30:24,080
i'm noticing an ongoing theme to these

2305
01:30:29,669 --> 01:30:26,719
questions as well um so you did mention

2306
01:30:31,669 --> 01:30:29,679
that you had some that obviously we've

2307
01:30:34,870 --> 01:30:31,679
always had some issues observing and

2308
01:30:37,030 --> 01:30:34,880
quantifying dark matter but

2309
01:30:39,510 --> 01:30:37,040
he said some dwarf galaxies appear to

2310
01:30:41,830 --> 01:30:39,520
have little or no dark matter associated

2311
01:30:43,669 --> 01:30:41,840
based on observation so far

2312
01:30:48,870 --> 01:30:43,679
do you find this to be a theme with

2313
01:30:54,310 --> 01:30:51,750
that's a good question uh this isn't

2314
01:30:57,750 --> 01:30:54,320
something that we've

2315
01:30:58,870 --> 01:30:57,760
explored with james webb uh yet

2316
01:31:01,189 --> 01:30:58,880
um

2317
01:31:03,350 --> 01:31:01,199
not directly at least what

2318
01:31:05,350 --> 01:31:03,360
the one thing i'll say with that is is

2319
01:31:06,709 --> 01:31:05,360
if we compare so the the standard

2320
01:31:09,189 --> 01:31:06,719
assumption is that

2321
01:31:12,550 --> 01:31:09,199
galaxies form within halos of dark

2322
01:31:14,310 --> 01:31:12,560
matter that the the dark matter and and

2323
01:31:16,229 --> 01:31:14,320
the evolution of the dark matter halo

2324
01:31:19,510 --> 01:31:16,239
and of the galaxy itself this so-called

2325
01:31:21,350 --> 01:31:19,520
regular matter is linked together

2326
01:31:23,910 --> 01:31:21,360
and our models and our observations with

2327
01:31:26,550 --> 01:31:23,920
hubble appear to agree

2328
01:31:28,709 --> 01:31:26,560
however this age dating let's say of the

2329
01:31:31,590 --> 01:31:28,719
stars and the fact that we're finding

2330
01:31:35,110 --> 01:31:31,600
now a lot more distant galaxies with

2331
01:31:36,870 --> 01:31:35,120
james webb does not agree with our

2332
01:31:39,669 --> 01:31:36,880
models of the evolution of dark matter

2333
01:31:41,590 --> 01:31:39,679
halos so it suggests that there could be

2334
01:31:45,110 --> 01:31:41,600
some something we don't understand some

2335
01:31:46,950 --> 01:31:45,120
apparent decoupling let's say um

2336
01:31:49,270 --> 01:31:46,960
so that's where the uncertainty sort of

2337
01:31:51,030 --> 01:31:49,280
arises we don't know if our models of

2338
01:31:52,950 --> 01:31:51,040
dark matter

2339
01:31:54,310 --> 01:31:52,960
perhaps are missing something it's

2340
01:31:56,310 --> 01:31:54,320
entirely possible we're missing

2341
01:31:57,510 --> 01:31:56,320
something or else

2342
01:31:59,430 --> 01:31:57,520
you know maybe we're looking at a

2343
01:32:01,669 --> 01:31:59,440
particular patch of the sky which seems

2344
01:32:03,030 --> 01:32:01,679
to have a lot of distant galaxies that

2345
01:32:04,950 --> 01:32:03,040
is representative

2346
01:32:07,270 --> 01:32:04,960
or something something's gone wrong we

2347
01:32:09,189 --> 01:32:07,280
don't know or you know it's it's great

2348
01:32:10,310 --> 01:32:09,199
that we have this to figure out but in

2349
01:32:12,629 --> 01:32:10,320
terms of

2350
01:32:15,270 --> 01:32:12,639
these dwarf galaxies which you mentioned

2351
01:32:17,350 --> 01:32:15,280
we have not done this sort of analysis

2352
01:32:18,709 --> 01:32:17,360
with these ultra distant characters

2353
01:32:19,910 --> 01:32:18,719
that's not something we've looked at

2354
01:32:23,030 --> 01:32:19,920
directly

2355
01:32:26,390 --> 01:32:23,040
only on a statistical level right

2356
01:32:28,149 --> 01:32:26,400
you know the as we assemble all these

2357
01:32:30,149 --> 01:32:28,159
all these observations and uh do

2358
01:32:31,910 --> 01:32:30,159
multiple fields and everything as the

2359
01:32:34,550 --> 01:32:31,920
statistics are going to get larger and

2360
01:32:36,950 --> 01:32:34,560
larger uh and we'll be able to tell are

2361
01:32:38,390 --> 01:32:36,960
we looking at special regions are we not

2362
01:32:40,550 --> 01:32:38,400
um

2363
01:32:43,189 --> 01:32:40,560
we're seeing a lot of galaxies all that

2364
01:32:45,750 --> 01:32:43,199
just all i can say is that uh that makes

2365
01:32:47,669 --> 01:32:45,760
it very exciting and so they're

2366
01:32:51,590 --> 01:32:47,679
i do not expect it to fit with what i

2367
01:32:55,270 --> 01:32:53,510
all right but it's wonderful that that

2368
01:32:56,629 --> 01:32:55,280
we're learning new things

2369
01:32:58,149 --> 01:32:56,639
that's what's great about it that is

2370
01:33:00,310 --> 01:32:58,159
science right if we didn't learn new

2371
01:33:01,990 --> 01:33:00,320
things we wouldn't be doing our job

2372
01:33:03,910 --> 01:33:02,000
that's right so after webb's been up for

2373
01:33:05,830 --> 01:33:03,920
a bit we'll have to have part two so

2374
01:33:07,750 --> 01:33:05,840
what you're saying most definitely this

2375
01:33:10,870 --> 01:33:07,760
this this is not the last we're going to

2376
01:33:12,709 --> 01:33:10,880
hear from guido on this on this

2377
01:33:15,270 --> 01:33:12,719
side that's right our next data set will

2378
01:33:17,830 --> 01:33:15,280
be arriving end of october or november

2379
01:33:23,590 --> 01:33:19,510
all right uh

2380
01:33:24,470 --> 01:33:23,600
until such time uh you also stay tuned

2381
01:33:28,229 --> 01:33:24,480
um

2382
01:33:32,629 --> 01:33:28,239
next month on october 4th the universe

2383
01:33:33,910 --> 01:33:32,639
of dante alighieri please join us until

2384
01:33:36,470 --> 01:33:33,920
that time