Deepest Ever Deep Field. Where Are The Limits of James Webb?

the Hubble Deep Field is one of the most iconic images in all of astronomy it's this time when they spent thousands of hours with the Hubble Space Telescope staring at a seemingly empty spot in the universe and what they saw were tens of thousands of galaxies out to the very limits of what Hubble could see and of course it's natural to wonder when is the James web Space Telescope going to do its version of the Hubble Deep Field it is so much faster so much more powerful than anything Hubble can do and already the initial tests that astronomers have been doing have shown just what is capable with a fraction of the time a James web Space Telescope Deep Field is kind of inevitable so my guest today is Dr vaj Panda he worked on the various flavors of the Hubble Deep Field has been working a lot of really interesting Galactic surveys using James web examining galaxies he's on one hand done some really interesting Research into the shapes of galaxies seen in the early Universe they're not what you'd think not the grand spirals or giant elliptical galaxies we see around us today but they were more like tubes as he calls them bread sticks and this was surprising and is sort of a really interesting field of study so far we spend about half of the interview just talking about what he has discovered with James web so far and then we shift gears and talk about what does the future hold for giant surveys when will we get that deep field and I think you'll find that part of the conversation as well really fascinating and get you pretty excited about what the future holds all right here's my interview with Dr verage Pano vage if you were to sort of describe the typical Galaxy in our neighborhood what would we see that's a great question Fraser so the typical Galaxy in our neighborhood it's it's a spiral galaxy so I have this analogy that I make uh inspired by working in New York City where if you think of galaxies as coming in terms of uh three different um dominant shapes uh you can think of elliptical galaxies that are intrinsically round in 3D so these are like um balls of dough that are perfectly round and then you take that ball of dough and you flatten it along one axis and you get the greatest thing in the universe you get a pizza and so the pizzas are what dominate uh in the local Universe uh and sometimes you can have pizzas with like balls of dough in the middle that we call bulges um these are these are um uh the most common and as you go to like the most massive nearby galaxies they start to preferentially become like balls of dough just like pure round roundish 3D balls of stars and those I mean I really do like that pizza analogy I I may borrow that um but but this idea I mean when we think about the Milky Way I mean we're not just this flattened disc we are surrounded by this cloud of satellite galaxies many that we have ingested so if you sort of look closer at at the various types when you see this the spirals when you see the elliptical do they have similar kinds of clouds of satellite galaxies around them as well yeah the Milky Way our own Galaxy um which which is it's like a spiral with a small um bulge in the center uh and a bar uh and and of course these spiral arms but it's also surrounded by this swarm of like 60 little satellite galaxies uh most of them we say are um red and Dead uh in the sense that uh most of them don't have any Interstellar gas the fuel for forming new stars there's a handful like the large and small magenic clouds which are two of the biggest satellites of the Milky Way uh that do um have gas they're forming new stars uh and then if you look at other nearby galaxies like Andromeda or you know giant elliptical um they also have their own satellite populations that are um orbiting as exactly you said like in a in a Halo um and that Halo you know is made of both is predominantly we think made of Dark Matter uh and we don't know exactly what dark matter is but we can infer its its presence um uh because uh affects the Motions of the Stars uh in in galaxies and that I I actually didn't know about that idea that that the satellite galaxies of the Milky Way are red and dead that that they used up their reserves of gas and dust for Star formation before they got sucked into the the larger Galaxy and so it's a you know when we look at the structure of the milu way thanks to say observations by Gaia we see the streams of torn up satellite galaxies that joined us in the past and so those ones I'm assuming did bring their gas and dust into the Galaxy yeah yeah so there's there's definitely like these two uh regimes so these like streams of stars like kind of strewn out like the magelan streem um these are the remnants of galaxies satellite galaxies that couldn't survive and they've been literally torn apart uh because of the immense gravitational pull of the Muki way Halo U but there's about 60 galaxies that are still like bound collections of stars um but they don't have most of them don't have any gas to form newars except for the LMC andc yeah huh that's really interesting okay um sorry I just rabbit hold there for a second filled in a gap in my knowledge um so then as we expand our view out to you know beyond the local group looking at say the Virgo supercluster Galaxy that are in the tens of millions to hundreds of millions of of light years away does this story change or do we just see kind of the same thing nearby yeah so as you go towards um like nearby clusters of galaxies uh which are like uh you know the New York cities of the universe where all the galaxies kind of hang out something does change in the sense that as you go to groups and clusters of galaxies you start to see many many more red and dead galaxies and also many more elliptical type galaxies um so it's kind of mind-blowing for me to think about about it this way but you know the Milky Way right now okay we're we're in this local group you know we have the Andromeda and another nearby massive Galaxy we have the triangulum Galaxy and then we have the smattering of satellites around the Milky Way Around the Andromeda galaxy and triangular scattered throughout the local group but if you go to say the Virgo cluster or the coma cluster the satellites in the coma cluster and the Virgo cluster many of them um you can think of as like milky ways so imagine like a Milky Way Mass Galaxy being a satellite around a factor of you know 10 to 100 times more massive Galaxy or Halo so it's like one stage larger structure than what we have around the Milky Way it's like I don't know like moons are to planets planets are to Sun and then in this case spiral galaxies are two giant Galaxy clusters exactly yeah and there's there's a you know long-standing puzzle um that uh when you go to these like large clusters of galaxies a lot of the the the inhabitants the the the the galaxies and these clusters um they don't form uh Stars at the rate at which they would if they were not in the cluster like the Milky Way today you know it's not great at forming Stars it's kind of uh average we we call it a Green Valley Galaxy as opposed to like a blue star forming one or a red and dead elliptical um but if you put the Milky Way in a cluster like coma it would be forming it would not be forming Stars uh its gas would probably get stripped and right right and so there like clearly there's this cycle going on at various scales we see it in the dwarf galaxies that are around the Milky Way and then you see the same thing but just at the next level up with their interactions in these larger Galaxy clusters okay so as we look farther out then say you know we bring the Hubble Space Telescope online and we start to look out to the very limits of where Hubble can perceive Galaxy structure what do we see and I guess how far away is that and how or how far back in time is that yeah so Hubble you know in principle it was it was able to observe galaxies uh back to you know a few hundred million years after the big bang but its sensitivity wasn't as great as of course now the James Webb Space Telescope but even with its You know despite that it's you know it it revolutionized our understanding of Galaxy formation and one of the things I like to point people to which is kind of Forgotten these days I think is in the mid 90s uh when people started to you know create some of the first like Proto Hubble Deep Fields uh they found that when they pointed at you know a relatively empty area patch of the sky smaller than the full moon um they found that as you look at distant galaxies um that existed maybe you know 10 billion years ago uh and including this includes galaxies that we think had the masses and star formation rates of like what we think the ancestor of our own Milky Way was so a lot of these Milky Way progenitors that existed 10 billion years ago Hubble found in the mid 90s and early 2000s they were very linear looking and as you started to approach the detection limit of the Hubble Imaging at the time you started to get dominated by these very linear looking structures Galactic structures and there were lots and lots of you know proposed explanations for this one is um maybe Hubble is just not sensitive to you know detect uh like the rounder looking thing so if you imagine you have a spiral galaxy like the Milky Way right so you can see it from a variety of viewing angles right um and it turns out that if you look at a Milky Way like like a spiral galaxy Edge on then it's it's going to appear brighter so you're more likely to pick it up in your in your observations but if you take this like thin disc this thin Milky Way spiral type thing and you put it face on then the light is more diffuse and it actually has a lower what we call surface brightness and so it's very likely that it'll kind you won't pick it up in your in your Imaging um so this was one idea back then that you know maybe we're seeing all of these elongated linear structures just because there's like a bias against detecting the face on WIS and this is actually a really big problem in astronomy I mean we experience this when you walk outside and you look up at the night sky you're seeing all these stars and all of them are weirdos right there are almost no star that you can see with your eyes outside except for a couple of close ones Alpha centuri things like that that are just the same kind of brightness as are as the sun and definitely not the most common stars like the red the red dor what you see are stars with many times the mass of the Sun stars that are hundreds of light years away each one of them is a bizarre rare very bright thing and so if you think as you look up in the sky and like that's normal it's not normal like there's all these hidden stars that you don't see just because they're so bright and I know that this problem comes up a lot with you know it's like almost like survivorship you guys have a have a term for this right but it's like survivorship bias like when you look in the field you're seeing a bunch of stuff it's biased towards the kinds of stuff that can be seen and that can totally skew your results yeah exactly so we call this a selection effect or uh this particular case yeah surface brightness detection bias yes like what actually makes it into your sample of observed galaxies and and I mean there there are ways to modify this so you know a lot of I think you know it's pretty standard like I've done this for my recent jwsd paper and you know people have been doing this for for as long as people have been studying galaxies you know you can you can take your the typical characteristics of your image or just take your image itself the images you've taken with your telescope and you can inject fake galaxies into those images uh and you know their properties you know where they are um you can assign them various uh different you know colors and and and and uh orientations and brightnesses and you can then run that kind of you know mock image through some detection pipeline to detect sources to detect galaxies and then you can once you do that you actually walk away with a better understanding of like okay here is the the limits of my data the detection limits of my data and and if I'm trying to draw conclusions about galaxies that are fainter than that limit I should be very careful because I don't right you know I'm missing I have severe biases maybe huh and I mean it feels like that should almost be like your instinct when you're running up against the edge of what your telescope can do you should assume by default that there are all kinds of selection biases going on there yeah that's exactly right yeah that's interesting all right so so you got this hint that there were these strange linear shaped galaxies were starting to appear more often the farther you looked back in time jwst comes on online now you're able to see even farther even deeper what do you see yeah so um so yeah I used uh I worked with an amazing team of astronomers 100 people uh uh and more actually um this is a collaboration it's an early release science collaboration uh for the James Webb Space Telescope known as Sears the cosmic Evolution early release science survey uh Steve finlin is the is the pi one of my former mentors as well um and uh so you know we saw these papers coming out in the first two years from jwst um which were convincingly showing that there were cases where Hubble had completely missed disc galaxies like they just weren't even they were just no noisy images from Hubble you couldn't make anything out but then jwst Imaging of the same patch of Sky reveals all of these nice discs including many face on ones uh and so there were a lot of papers about this and claiming that uh you know the the fraction of galaxies that are classified as discs and Hubble Imaging drops dramatically as you look further and further uh to larger distances um but then the fraction of disc galaxies according to James web Imaging it was at like the 40 to 50% level um so where where it was like less than maybe you know a percent or 10% in in Hubble Imaging uh it was you know the disc fraction was 40 to 50% so I got very excited because you know I thought okay well well jwst has solved this puzzle where maybe it's detected all of these round you know face on discs that Hubble had missed and we don't have a crisis you know maybe there's uh there's no there's no uh puzzle anymore to explain these linear things this this overabundance of linear Galactic structures so I actually went in with the sear team and we actually um you know character the the essentially the distribution of the projected ellipticities of of all galaxies in the in the SE jbst Imaging so what that means is you you know you have you have you have galaxies on the on the sky you know 2D Sky they're projected and you can essentially fit every Galaxy with with some kind of ellipse right and then you can characterize every Galaxy by the ratio of the short axis to the long axis of of of its best fitting ellipse that's called the projected axis ratio and then for Galaxies that are like at a similar distance from us and that have a similar mass or brightness we can just do a simple counting exercise we can just look at the distribution of that projected access ratio projected ellipticity and if you sorry go ahead yeah no well it's just going ask so like if you like you have done enough calculations for different kinds of galaxies so that when you see a certain shape in the sky you're able to calculate what its orientation is compared to us as the Observer and then you can do that at scale like you can see a whole bunch of galaxies in a field your computer algorithm can run through them all and go this one's pointing this way that one's pointing that way this one and so on and be able to sort of do a giant survey quickly yeah exactly um and and you know this is a statistical exercise I can say some more uh later about you know ways to follow those up to get Smoking Gun measurements constraints on the orientations of individual galaxies but you know when we when we measure the projected orientations the projected shapes of these galaxies uh we have certain expectations so you know if we think that the universe is isotropic in terms of you know galaxies being randomly distributed throughout it and randomly oriented um and and in our standard picture right if we think galaxies start out as spirals as discs then you should see discs from many different v um and so you actually end up expecting a roughly uniform distribution of galaxies with different axis ratios you should see equal numbers of round ones and equal numbers of Edge on ones like like you know like thin lines and we don't see that even with jwst we don't see a uniform distribution instead the distribution is very asymmetric uh and it's skewed heavily in favor of still like these these uh elongated linear looking galaxies even with the improved sensitivity of jwst and that's telling us that you know these early galaxies like like the ancestors of the Milky Way that existed 10 billion years ago they cannot all be like spiral galaxies like pizzas um and they also can't be balls of dough which would preferentially show up actually looking round no matter what you look at a ball of dough it's going to look round in projection so there's a there's actually another possibility that that my co-authors and I are advocating for and this is um the the to complete the the New York City you know baked product analogy right we have doughballs you have pizzas now take the pizzas and flatten them along one of the other two axes and you get my other favorite thing in the entire universe you get a bread stick right right okay so so bread stick is like this third class of of uh types you know the the the it's called an ellipsoid a prolate ellipsoid shape um and you know we think that we're seeing lots and lots of galaxies at Early times that maybe in 3D are shaped like bread sticks they're not like nice circular discs they're heavily flattened along a second axis um and so what you know so if we could fly close to one of these things things and take a look at it you know like if we were like Andromeda close um what would we see that's a great question so um so yeah you can do a little thought experiment if you fly up to one of these these uh these bread stick or cigar-shaped galaxies in the early Universe you know we think what you would see is lots and lots of other little galaxies maybe uh undergoing kind of they're on very radial orbits so they're kind of undergoing um in the process of undergoing mergers essentially along a preferential Direction um so our standard thinking right now for why these galaxies are shaped like bread sticks is they are embedded in Dark Matter Halos right like we talked about for the milkyway um but the Dark Matter Halos of these early galaxies they're not like the relatively roundish Dark Matter Halos of the Milky Way today we think the Dark Matter Halos of these early galaxies that are Red Stick shaped are also elongated so they're the Dark Matter Halos are also like scaled up versions of like a breadstick shaped ellipsoid um and that dark matter Halo's longest axis is oriented in the same direction as the long axis of the stars and finally this entire system we think is embedded in a dark matter um Cosmic web filament uh so you you talked about you know we talked about um clusters of galaxies before right and so these are found at like the intersections of cosmic web filaments uh and filaments are you know where we think like the characteristic typical Galaxy like the Milky like Milky Way progenitors like where where typical galaxies form they form in filaments and they make their way towards these clusters over cosmological time scales and so back to that idea if I was looking at the at the Galaxy Andromeda distance away I wouldn't see like a a two armed I don't know Galaxy that would you know had a central bulge and then one arm leading forward you know in a straight line I would see like this giant collection of dwarf galaxies that are all together in a line merging and star forming and and beginning the process of coalescing together which is which is different from what you would have originally expected that it would be like the they'd be coming together in a kind of spinning disc but you're seeing in fact it's like this weird line and and that matches the the larger scale structure of the universe Cosmic web the the sort of the amount the distribution of Dark Matter that's believed to be to be out there yeah that's right and another really yeah I mean another really cool thing about this I wrote a paper about this 2019 and it's how I got I first became aware of of this particular area you know of of Galaxy formation so my my advisers at the time Joel primac Sandy Faber David coup and aish Shai deal you know we had this idea that if galaxies if these linear looking early galaxies were in fact what I'm what I'm saying that that they're like these collections of little you Galaxy undergoing mergers along a preferential Direction and they're they're embedded in these dark matter filaments well something else you might expect to see is actually these linear looking bread stick shaped galaxies may actually Point towards one another in 3D um if they're forming along you know if there's like multiple of these bread sticks forming along filaments and so if you take yourself back to Earth and you look at the 2D projected sky um you know we we expect that maybe in projection these early galaxies on the sky are not going to be randomly oriented they're going to maybe Point towards one another on average and this is something that we can will be able to get a handle on and directly map out um with the upcoming Roman Space Telescope in a few years right so so in other words if these lines are the progenitors of the larger spiral galaxies then the then the next step that you should see is these streams of stars crashing into each other and then actually beginning that star formation sorry beginning that that larger spiral galaxy formation and I guess the the ones that are kind of trailing behind that are going through their star formation they end up as those satellites that don't get fully consumed by the spiral yeah that's right we don't know exactly how how um one of these bread stick shaped things will turn into a spiral like the Milky Way um there's you know we we do have very high resolution simulations of the universe of individual galaxies like the Milky Way and their evolution you know over billions of years at Cosmic time and these simulations um by for example Daniel seino and Joel primac and and aish Shai deal and others they do suggest um that that there's some process you know in the beginning these these galaxies are shaped like red sticks and then they continuously undergo mergers and they form stars in their centers so over time you get a increase in the central mass density of stars and during the bread stick phase Stars can actually go arbitrarily pass arbitrarily through the center of of the Galaxy which is in contrast to like a Milky Way spiral right where the stars are on circular orbits they don't generally go through the center they kind of just stand in circular orbits um but in these bread sticks you know you have a growing mass density at the center of the distribution because you you have mergers maybe you have cold flows of gas towards the center that form stars and so these St these stars that are on initially kind of radial orbits through the long axis through the center of the system they might start to get deflected um they may start to get deflected off of their original orbits because of the central mass density collection of stars that's growing and the entire system May kind of puff up and and how exactly that process then leads to the formation of a disc or a central bulge is is not well understood at all it's very complicated and maybe chaotic but well I think of an analogy with like the lrange points like think about The L4 L5 lrange points which lead and Trail the sun in the in the solar system and you get this very chaotic system of these objects orbiting around inside of it but the way the torqus work if one of these objects starts to drift out or has a three body interaction and drifts outside of the of where it is it experiences a a torque that pushes it back into the region and and creates this sort of giant fluffy mass that is perfectly related to the gravity of both the Sun and the Earth but they're also trapped there and so you can sort of imagine that as these things are trying to escape the the larger Dark Matter strand is is sort of keeping things constrained it's it's it's it's very bizarre I mean I think as you think about the shape of the Stars you must just spend a lot of time thinking about the that invisible larger scale Dark Matter structure if that's driving it then you're seeing its Echo Its Reflection its you know shadow in Stars yeah yeah no it's it's really exciting this is this is why we we want to do a couple follow-up um studies uh and one of them I just mentioned you know earlier is we want to go in with the Roman Space Telescope in a few years and ask do we actually see these galaxies tracing out like you know on huge scales like these kind of strands the filaments in projection on the sky at different distances from us because that would be a nice kind of smoking almost Smoking Gun test um no one's ever detected strong like strong intrinsic alignment signals as we call them in in in the field no one's ever detected them for like these low mass galaxies we've known for a few decades now that like the most massive you know red and dead elliptical at the centers of clusters actually Point towards the ellipticals at the centers of other clusters because uh they retain their memory of their you know initial formation uh and and um so that's one thing thing um and then the other thing is we want to try to um it's very challenging to do this but you know there's this kind of um there's this fundamental issue for individual galaxies if you see any individual Galaxy that looks like a linear structure and projection no one can say like from the James web Imaging alone is this elongated Galaxy and projection is it a circular disc in 3D is it an oval disc is it one of these bread stick shaped or cigar shaped things um the The Smoking Gun way to test that is you actually have to get a spectrum of the Starlight of this thing and that's super challenging because these things are so small they're so faint they're so far away but if you can do that uh and if you can detect um the absorption lines uh from the stars in these galaxies then you can actually tell what kind of orbits the stars are on so if you have a circular disc seen Edge on you know you expect the Stars to be on circular orbits so you expect to see a rotation curve one side will be you know moving away from us and one side will be moving towards us as the stars orbit on C circles um but that's literally impossible for you know if these galaxies are like highly you know Red Stick shaped or surfboard shaped is another beach themed analogy I throw in because there we expect the Stars to be on these highly elliptical radial orbits along the major axis um and so we are starting to think about you know ways to constrain this with uh existing telescopes like of course James web but then also the kek telescope in Hawaii but I think uh we really uh need the next generation of 30 metor class telescopes the the elts the extremely large telescopes which will come online you know the European one may come online in 2029 before the end of this decade and then the two hopefully fingers crossed the two US ones the giant mellan telescope and the 30 meter telescope will come online in the early 2030s so you must have done the calculation though you've got a proposal rattl around in your brain that says I need this many hours on James web to measure to get gather the Spectra from one of these galaxies to measure the rotation curve right yeah what's that number how many hours do you need so for I've got some Spare Time on James web you can have it how much do you need yeah that would be awesome um it's going to be uh a several hours at least um because I think the you know the the real data that I want um is uh there's a there's an instrument on James Webb it's called um the near infrared spectrograph uh and it has a Mode called the integral field unit mode where essentially like you have a Galaxy and across the face of the Galaxy you can get Spectra at many different points along the face of the Galaxy which lets you then you know if you can go deep enough um and integrate for long enough then you can get like the you can get constraints on the orbits of the well what what is the um the velocity the velocity field of uh the gas in the Galaxy which is an interesting constraint in and of itself um but it's going to be very challenging to get it for the for the Stars so it's going to be several hours and we'll only be able to do it for the brightest biggest ones right but I mean several hours that's fine that's acceptable I think approved yes you're welcome yeah I I would love some of your your your yeah your time yeah yeah no problem um all right so I want to shift gears now and just talk about these large web surveys in general I mean people are entranced by the idea of the Hubble Deep Field that you took this telescope stared what you thought was an empty piece of space and upt tens of thousands of galaxies so what is the equivalent of that for web right now yeah so I would say you know we have uh we have several surveys um seers is one that I've been involved with um there's there's a couple others that I've already been completed or nearly completed like Jades and NG deep um uh that are going significantly deeper so they're integrating for even longer than Sears integrated for these are great but they're still relatively small areas in the sky uh so there's other surveys also that are a little shallower but they're trying to get you know they're trying to cover a you know somewhat larger portion of the sky so for example Cosmos web um and I think what we we're GNA see you know we're going to continue to see more and more of these like super super deep uh you know the the the James web deep Fields uh but those are GNA those are only going to be in a tiny fraction of the sky just like the Hubble Deep Field because it's so expensive and I'm I'm on a few of them actually you know there were proposals every year for for getting time and this is like I think the first year where the um astronomers at large put in uh huge we call them treasury proposals uh because we want to you know create the this wealth of like data set that data sets that U Imaging and spectroscopy that will you know serve the community for for for for years and years down the line um so these like Ultra super deep jwst deep fields that people are planning now they're going to be able to detect you know red shift 15 20 galaxies that James Webb was was was designed to do right uh you won't you won't resolve those galaxies but I mean give me a sense of that I mean I know that when Webb first came online a lot of people were making a lot of claims about the most distant galaxies that they were seeing and we were seeing numbers like red shift 17 you know numbers that are like two to 300 million years after the big bang and things have settled down people have calibrated better and now we know we're more in the 400 milliony year regime and not in that in that earlier regime what kind of time is involved like like when I think about web and you know they always talk about like or when they think about Hubble they talked about like how many hours it took and how many orbits and how many you know here's the field of view and here's the the most distant galaxies that are being seen so so give us a sense because I like web is so much faster than Hubble was and so give me a sense of like if you were to like take the telescope and point it at one spot in the sky how long would you want to point at that spot until you started to resolve those those red shift 15 plus objects or detect not resolve them yeah so just to give you a sense of scale um you know I was I was a member of one of the largest Hubble Space Telescope collaborations um that kind of pull together resources from The Wider Community to um take up almost a thousand orbits of Hubble uh wow to to create you know we always talk about the Hubble Deep Field right because that's like the the OG uh but there's actually five there's five deep Fields um that are in like non you know strongly crowded non- strongly lensed regions um so there's a Hubble Deep Field North Hubble Deep Field South uh and then there's the ultra deep survey there's the extended growth strip and then there's a cosmos field um and each of these right if you go into each of these These are five different fields on five different parts of the sky uh sear is in actually sear observed um uh the extended Groth strip part of this candle survey the cosmic assembly near Fred deep extra Galactic Legacy survey from Hubble um uh so each of these five fields from Hubble um you know that your tiling observations because Hubble has a relatively small field of view so you're tiling observations to create like a mosaic um and for any individual part of that tile it's about uh two months of observing time to get to the depths of a Hubble one one one object in the Mosaic one tile in the Mosaic is that long is about yeah it's about 50 days or so yeah wow for some of these yeah so that's about two months of observing time for one part of this bigger Mosaic for yeah yeah from one of the five deep fields from Candles now Hubble like with Sears right we went back to one of these deep Fields the extended grth strip and uh for any individual part of our Mosaic comparable to candles it wasn't it wasn't two months it was less than an hour right and with less than an hour we actually see way way more substructure yeah than Hubble did um which makes sense I mean you know Hubble is a 2.4 meter you know um telescope and James Webb is a 6.5 meters so it's a bigger telescope more light collecting area um improve you know detector technology um so but that's just mind-blowing to me that you know 50 days versus 50 minutes and the stuff that we see with James web is just way you know just way deeper now yeah and I remember we reported on on this it feels like about a year ago there was like versions of this and they were finding many more galaxies that are in the Hubble Deep Field like just already like without even trying it's already vastly surpassed the capabilities of of the the same regions of the Hubble Deep Field and these are tests these are just like can we do this right yeah yeah exactly yeah and so yeah I mean the the like the limiting you know going back to detect you the detection limits of your data right like the limiting magnitudes of some of these early jbst surveys are already comparable to if not deeper than than than hubbles uh and you can you can resolve a lot more substructure in some of these galaxies so you know with Hubble or with James web and Sears which again is not the deepest data that we already have available compared to like Jades or ngd but with Sears you know my paper we did like these detection limit tests and we showed that we are going at least a 100 times fainter with with sear Imaging in terms of like characterizing the outskirts of of galaxies that are you know maybe existed 10 billion years ago um compared to Hubble Imaging so but if you if you just you stared with this new capability how how long is a reasonable no not even a reasonable how much is an outrageous amount of resolution to get I mean it if 50 minutes gave you more than Hubble what would 10 like there must be a limit is 10 hours enough for one piece of the sky 20 hours what's what's the point where you said okay this is we're hitting diminishing returns at this point yeah that's a great great um great question um yeah admit I haven't thought about that too much uh but um as people are starting to plan this uh you know I think I think at least trying to be as ambitious as we were with with the original Hubble Deep Field kind of staring at the same patch of sky for maybe you know several tens of hours straight uh uh to see how many more faint sources we can pick up um AKA yeah I mean very high R of sources I think that's definitely uh feasible I mean it's always a balance right between between depth and width I mean you could point at for one hour at a time and move your field of view and you would reach a certain depth and a certain faintness of object and you would be able to tell a story about the sky that would keep astronomers fed for a decade but if you then double the time triple the time 10 times the time that would allow you give you less of a field of view but you would see fainter objects and and I wonder like I'm sure at some point someone is going to have to make this call and say okay when we do the James Webb deepfield yeah we get two hours per frame for the Mosaic or we get 10 hours per frame or we want a 100 hours like do you have any sense of of where those diminishing returns has nobody done a paper on this what where are the diminishing returns because they exist in hble like you must be deeply familiar with where diminishing returns are for doing these kinds of observations with Hubble yeah why does nobody know this for James web yeah I know people are thinking about this I don't I don't think about the planning of you know the eventual James Webb deep Fields myself um but uh certainly um you know I think not only is there going to be trade-offs between uh like depth versus width of James web um just given Maybe are existing predictions for how many you know how we think the number density of galaxies evolves is a function of of of red shifter time there's also like kind of balancing what James web's capabilities are currently with you know when it eventually overlaps with the Roman Space Telescope because Roman I think is going to be the real player in terms of Widefield surveys right because a single pointing with the Roman Space Telescope is equivalent to 100 Hubble Deep Fields uh it won't go as maybe as deep as like James web um initially but people are planning you know large community surveys with Roman um and and Roman is going to have near and fret capabilities it won't be as sensitive as James Webb because it's a smaller telescope 2.4 meter like couble um but you want to I'm sure people want to um are thinking about balancing you know upcoming facilities and then the coverage with James web but yeah and it feels like that's like you're looking to do why you know do the entire sky with NY Grace Roman and then do one very specific part with SE web and then compare and say okay great when we see stuff at the very detection limits with Roman then we know that that means that there are these kinds of things in that region right like it gives you it's like your Rosetta Stone between the two regions but I just wonder like if you just pointed web at one spot in the sky for 10 hours 100 hours like are you going to start to hit the Epic of reionization are is are you going to get a time when there's just like too much Sky glow from from dust in the in the solar system like I wonder what the limit is like what is the limit of web yeah that's a really good question I haven't thought about that to be honest uh uh yeah no that's a that's a that's a good question um okay well it's fine you don't know the answer it's fine yeah weird it's I I'll keep looking because because it feels to me like like that I mean that question was asked with Hubble and the answer was gravitational lenses right that that the the way we see deeper with Hubble Is We you we look for natural telescopes those let us push to the very limits of what's capable and we're limited by the best gravitational lenses that we find and the most interesting objects that are being lensed by those like and and a gravitational lens gives you whatever 10,000 times 30,000 times resolving power that Hubble could do on its own and so you're you're not going to be able to do better yeah but and you get Spectra and you know yeah and and the same things but in theory the whole point of web was that it could do the kinds of things that Hubble can't do directly without the lensing without the lens it just sees it and so I just wonder if you just turn that thing on and let it run 10 hours 100 hours certain point you go you know we're not getting any more information out of this picture right yeah we can't yeah yeah that's a really good point I yeah I I truly I haven't thought about that the like what are the limits like just from if you have so much data that you just can't yeah that point yeah just becomes like your yeah and it might be we won't find out for a while because the telescope is so over subscribed right that there's a million things to look at that are more interesting you don't really care about what the ultimate limits are but you know I wonder what questions could be answered because then there's like you know they originally plans like say the origins telescope that was going to Y follow on to web and that was going to be an even larger telescope that would take you even further back in time yeah it's I was just gonna bring that up yeah yeah yeah and it's being mashed into lir and and habex and you're creating this hital worlds Observatory which is yes I can't wait for that but we also lose the gigantic infrared telescope Next Generation so yeah yeah I actually just gave a a talk um so NASA was interested in you know what can the habitable worlds Observatory do for this kind of Science of constraining the the 3D shapes of these early you know Milky Way ancestor galaxies and I mean it's going to be insane I'm a little bummed that that the 2020 decadal survey recommended like there there were two versions of the habitable worlds Observatory which is itself kind of now a you know the best of habex and lir as you said uh and lir in particular there was like a 15 meter version and then there's an 8 meter version um and the dec said you know given the constraints on like uh coming up with the technology the engineering challenges and the funding challenges we can only recommend the 8 meter version um but even with the 8 meter version you know you'll get like 100 parsec resolution in in galaxies that existed 10 billion years ago so like red shift 2 red shift 3 Milky Way progenitors you get 100 megga par 100 100 parsec resolution um and you know you'll be able to like detect individual like Star forming regions um with like the level of detail that you know we expect for some nearby galaxies today uh and so you know that's going to offer important Clues on like well yeah what is the 3D structure of these early galaxies and how do stars form you know the stars that we see today in the Milky Way that are 10 billion years ago where were they forming in the Milky Way progenitor right R to and so when people ask me about the the when are we going to see the James web Deep Field I mean there is Cosmos there's there's tears there's was it Cosmic Cosmic web there's there's Jade so there bunch of smaller surveys but but according to you the there is a group that is starting to think about what does our version of the of the Hubble Deep Field look like and yeah it'll get proposed and then it'll be run and it'll come out so we're we're still a couple of years away from that would you say yeah I would say we're at least two to three years away because yeah this is the first cycle where I've seen you know the proposals were due last November um and you know part of some of these and uh you know they're still being evaluated by NASA and the Space Telescope Science Institute um we'll get decisions probably in the next month and then it will take you know a year to schedule the observations um but even these right the the proposals that were submitted and may get accepted this cycle these are still like individual teams of okay 100 astronomers each but if you kind of go back and think about a survey like candles on the Hubble Deep Field uh on Hubble right um like they originally two big teams of 100 astronomers each and they actually uh they both put in a proposal to do essentially very similar types of science you know go extremely deep you know 50 days of integration for individual parts of the you know Mosaic um of these five deep fields in Hubble uh and NASA and the space Cal Science Institute actually said well you guys should come together and you know we'll award you both jointly the time and that's how we got these five Hubble Deep fields from candles and also the frontier fields are another big thing as you said which were which were targeting strongly lensed you know Parts where uh where you have massive foreground Galaxy clusters um and so we're probably we may end up seeing something like that in the next two three years where lots of individual teams want to you know observe their favorite field but you know we might need like a community kind the community come together and say well we'll have one big collaboration and we'll all share the time and then everyone will benefit from the data so the data will become immediately public uh and we'll also provide you know to the community our our our you know our codes our models um our properly reduced processed Imaging so then the community you know like this this move towards open- Source science uh the community can can do the science that it wants to do oh it sounds fascinating I'm really looking forward to being able to report on on that so and hopefully you know we're just a couple years away from that well Raj thank you so much for taking the time to chat with me today I really appreciate it congrats on the work that you've done so far and I think you know we're still only a couple of years into this whole process with this amazing telescope so the best is yet to come yes thank you so much Fraser this was a lot of fun and I'll look out for your for your future podcast okay thanks I hope you enjoyed that interview I'm going to give you some more thoughts in a second but first I'd like to thank our patrons thanks to Paul roorbach Abe Kingston hey Twi douge Stewart Steven kosaki David Richards Mark Anis Joel yansy Anton lilara Dustin cable Vlad chipet moo George DAV Gilton and Andre gross Jeremy M Josh Schultz and Jordan Young Who support us at the master of the universe level and all of other supporters on patreon okay so stop asking already we got the answer which is that we are in the initial stages of the preparation and plans for a proper James Webb Space Telescope deep survey now there are a lot of existing surveys there's the Jade survey there's the Sears survey there's the cosmos web survey and each one of those is serving one tiny part in the sky and already they are turning out more galaxies in the fields that they're doing then giant swss of the Hubble Deep Field and this is just the appetizer for what is yet to come but right now all these groups are coming together there may be multiple surveys in different regions of the sky maybe one for empty spot one for a place that has a lot of gravitational lenses maybe something else interesting or maybe the groups will be merged together into one super group and then they will apply for time together but when you think about how web was able to do in minutes what took Hubble days that what we're going to get out of these surveys should be just as iconic and as memorable as what we saw with the Hubble Deep Field so I am really excited for what the future holds I had a really fascinating interview with Dr Adam ree who has also been using the James Webb Space Telescope but to measure the distances to galaxies with more precision and accuracy than anyone has ever done before so if you want more about James web here's a link to that interview all right we'll see you next time

Channel: Fraser Cain

Views: 200,410

Keywords: universe today, fraser cain, space, astronomy, exoplanets, James Webb, jwst, James Webb space telescope, tess, Ariel space telescope

Id: WdTkH1v2NqI

Length: 54min 1sec (3241 seconds)

Published: Sat Feb 10 2024