Zehra Karakilic
Welcome to Longitude Sound Bytes, where we bring innovative insights from around the world directly to you.

As part of our series focusing on the James Webb Space Telescope our conversations aim to shed light on the contributions of scientists for helping us understand our universe better.

I am Zehra, a student at Tilburg University pursing a degree in neuroscience.

For this episode, I had an opportunity to speak with Jeyhan Kartaltepe from Rochester Institute of Technology, where she is an associate professor of Physics and Astronomy.

Jeyhan studies the distant universe, and she also conducts research on how galaxies first form and evolve over time using telescopes on the ground and in space. Furthermore, she is a leading member in several large collaborative multiwavelength surveys, including COSMOS.

Her COSMOS-Webb project team received one of the first grants to study the initial images from the James Webb Telescope, so I wanted to speak with her about her work and the unexpected findings she has encountered.

We started our conversation with her pathway to astronomy. Enjoy listening!

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Jeyhan Kartaltepe
I always liked astronomy, even when I was a little kid, because I partly liked the weird stuff. I always liked learning about space and I would ask my dad, you know, random questions about planets and other things. So, I think it was always fun for me and interesting and so far, removed from what we do and see, on a day to day basis. It seemed for me a natural direction to go in, to read and learn more about. So, it seemed natural to start to study in school. And then of course in school, you see the kinds of jobs that people around you do. They’re teaching classes and they are professors. And it seemed like that would be a fun job to do.

My work is all observational. So, it’s all done using data using telescopes. I’ve been involved with projects involving Hubble and the Spitzer Space Telescope and other telescopes. And so, JWST is kind of a natural extension. It’s something that the whole community has looked forward to for many, many years, and through its development and all the delays and just kind of the exciting next step in terms of having capabilities that we haven’t had before. And so being able to study things we haven’t been able to study before.

Zehra
I find it really fascinating to see what we can actually find out about the galaxy and about space, and that there’s actually just more than beyond our little world.

Jeyhan
Yeah. And it’s hard to believe we can learn about things that are so far away, or about the beginning of the universe. It sounds like science fiction, right? So, it’s one of the fun things to talk about, when teaching a class, like how do we actually learn about these things that are so far away that we can’t actually touch but what can we learn from their light?

Zehra
Could you maybe explain in a few sentences, the mechanism that makes up the telescope like the JWST?

Jeyhan
The most important part of a telescope is the mirror. So JWST has a large, about 6.5 meter in diameter mirror. It’s segmented. So, it was put together in pieces to make it easier to assemble, fold up and put on a spacecraft to launch so it’s a bit unusual that way. It also has a secondary mirror. So, there’s a big mirror, and then there’s a smaller mirror that, you know, the light reflects off the big mirror and then on the smaller mirror and then gets sent down to the cameras.

The other most important piece of a telescope is the cameras. You have to collect that light, somehow. The different cameras have different functions. They can collect data at different parts of the spectrum. JWST is optimized for the infrared part of the spectrum, but the infrared is a pretty wide range. And so, there’s instruments that are suited for the near infrared, so closer to the visible part of the spectrum that we see. And there’s others that are designed to work in the mid-infrared. And then there’s some that take images that just take pictures. And there’s others that take spectra.

Zehra
Yeah, so I also wanted to know a bit more how the whole infrared observing works.

Jeyhan
There’s a lot of reasons why the infrared is really important for astronomy, especially for what I do, it’s really important because our universe is expanding. So that means everything’s moving away from everything else. So, it has a motion. And anytime something moves, the light that it emits, is actually moved to a different part of the spectrum. So, for galaxies in the very distant universe, the light that they would emit in the visible part of the spectrum that we would see is actually moved all the way to the infrared. So, we need the infrared to be able to see their sort of normal, the invisible light that we see.

There’s also a lot of processes that emit in the infrared. One of the biggest is dust. Dust seems like it wouldn’t be important but it’s very important in space. Dust is particles in space that eventually form planets. And so, things like wanting to study planets or planet formation around stars, you need to be able to see that in the infrared dust in galaxies, regions that are forming new stars. You can see that in the infrared.

Zehra
That’s really interesting to hear about all of this. I wanted to ask also just generally, how this whole concept started with your project, and how long would you say it took to develop it?

Jeyhan
I guess there’s a long answer and a short answer. So, this project that we’re leading, it’s called COSMOS-Webb, it’s observing a portion of the sky, that’s known as the cosmos field. And it’s something that I’ve worked on this particular field of the sky for almost all of my career. I started in graduate school when the first Hubble data of this area was taken. And so, over the years, you know, people have taken more and more data, because ideally, you’d like to have data across the entire spectrum to study all kinds of different objects and all kinds of different physical processes. When there was a call for proposals for JWST this was kind of a natural extension, like, Hey, we should really have the infrared data here too, because that would be fabulous but it took a while to work on it. Because of COVID, everything got delayed, which in a way sort of helped because it gave us more time to work on the proposals, to kind of hash out what we wanted to do. We had meetings like this one on Zoom every week, where we kind of talked about different ideas and different strategies, and what could we do if we did it this way or that way. And so, it really did take a long time to flesh out what we wanted to do. I think we were, in a way, kind of lucky to have that extra time to put it all together.

Zehra
It sounds such a complex project, what does your work environment look like? Like with who do you work with? Other astronomers, or maybe engineers?

Jeyhan
We have collaborators that are all over the world. So, we’ve been using zoom for many years, before it even became popular. A lot of people based in Europe, a lot of people based in the US, quite a few in Japan. Those are kind of the main places, and that includes people like me, or faculty that includes students. There’s a lot of graduate students that are involved, that includes postdocs. So, it’s a pretty broad range of people but for the most part, all scientists.

Zehra
What would you say is a typical day at your work? Like, how would you describe it?

Jeyhan
I guess it depends. Generally, my time is kind of split between teaching, which is kind of 20 – 30% of my time, something like that. Doing other universities support work, being on committees, evaluating student applications, you know, those kinds of things. And then about half of my time is devoted to research, but my research is really split into my own research where we’re working on things and working with my students. And so, I have a group of students and postdocs here that all have their own projects. And so, a good chunk of my time is spent working with them and meeting with them and talking through things. And ideally, when I have some focus time, and it’s spent writing, or programming. Those are kind of the two sides of things, you know, analyzing the data, which involves us a lot of coding and making plots and things like that. And then writing. Either writing the papers or writing proposals to obtain other data or obtain funding, things like that. So, you know, 90% of my day is in front of the computer.

Zehra
Do you also have like a student team that’s like helping out with the project?

Jeyhan
Yeah, I have several students here working with me on different projects. A couple of them are working on the COSMOS data and I have a couple of postdocs as well that are working on it.

Zehra
It’s really nice. I think it’s so important as a student to gain some research experience, which is quite hard sometimes. Especially working on such a big project and I think it’s probably very valuable in general.

Jeyhan
And it’s, it’s perfect timing for students right now. Because this is all new and exciting. So, I think it’s potentially grabbing the interest of students that might do something else, but then they see this cool thing and like, Oh, I could work on that. So hopefully fun for them.

Zehra
Could you also speak about so when you look at the universe through like a space telescope, how is it different than, I don’t know, like the telescopes on Earth? How is it more advanced? Or what would you say are the main differences or the similarities maybe also?

Jeyhan
The big difference of going to space versus being on the ground is to not have the atmosphere in the way. So, Earth’s atmosphere causes a lot of problems for observing. I mean, we need it so it’s great that we have it, but you know, if it’s cloudy, it’s cloudy. You can’t do anything about that the light is blocked. The atmosphere is very turbulent, right. There’s always stuff moving around. So that impacts how well you can see things because it kind of bounces light, you know, through the atmosphere on its way to the detector. So, by going to space, you can have much more detailed images and much more sensitive images. So, you can look at things that are much fainter, that you couldn’t see otherwise. And it’s especially true in the infrared because our atmosphere emits a lot in the infrared. And so, it, kind of, can block out certain parts of the spectrum, just because it’s already really bright there. So, you can’t see things that are faint behind it. So that’s really the biggest thing. Of course, the negative is that it’s expensive to put anything in space. And it’s difficult. So, you know, putting a big telescope is just technologically challenging. To get everything, kind of like JWST had to fold up, you know, to fit in the spacecraft, whereas on the ground, you can build bigger things, and it’s a little bit easier.

The other thing about going to space is temperature. Things can be kept really, really cold, which is again, important for the infrared. Things that are warm, emit light in the infrared, right, that’s how like infrared goggles and stuff work by looking at heat. So, you need to be away from Earth’s heat source to be able to do much in the infrared.

Zehra
Could you also talk about the COSMOS-Webb survey and what your whole role there is or your position?

Jeyhan
I’m one of the PI’s. I have a collaborator, Caitlin Casey, who’s at UT Austin, who’s the other PI, so we’re leading the survey together and the goal of this survey is to cover a relatively large area of the sky.

So, there’s kind of two different ways people go about surveys of galaxies. You can either look at one part of the sky, just take like one image, but sit there for a really long time so that you can collect more and more light, like a really long exposure and look at really faint things. So, then you don’t cover a large area, that’s a small area, but you look really faint.

The other strategy is to not expose for as long, so not to look as faint, but then to kind of map out a larger area. So instead, you’re covering many more galaxies, but more of the brighter ones and less of the fainter ones. In reality, people do both. The COSMOS-Webb survey is sort of that wide area. So, it’s wider than any of the surveys that are going to be done. Which means the huge benefit of that is statistics in some way. So, we’re going to observe, you know, hundreds of 1000s of galaxies, rather than, you know, 10,000, or something like that, like other surveys might have. And that also allows us to study sort of large-scale effects, large scale environments. So, if it matters, you know, whether something is really isolated, or whether something lives in a really dense environment, it’s like comparing things that happen in cities versus things that happened out in the suburbs, or in the rural area, you need kind of like a wide map really to be able to, to cover everything to see how things change.

Zehra
So how do you determine, like, the specific focus with the area, like, which wide range of the galaxies to pick?

Jeyhan
The area we picked is an area of the sky that people have studied for a long time. So, we already had data from other telescopes. So, you already have information in other parts of the spectrum. That’s really useful. So, you don’t have to go back and try to collect that after the fact. We want to study areas that are relatively free of like nearby stars, and things that are gonna get in the way. There’s gonna be stars everywhere but there’s certain parts of the sky where all you see your stars and certain parts that are more empty. And so, you have to choose an area that’s a bit more empty. It’s also in a part of the sky that we can observe from the ground from both hemispheres. You know, there are some parts of the sky you only see from the north or only from the south, this field is kind of on the equator. So, you can see it from anywhere, which is good for using other telescopes.

Zehra
Could you talk about if you already have some findings, such as achieved with the COSMOS-Webb survey, or how you think this could improve our current knowledge about the previously done studies, maybe?

Jeyhan
So, the biggest thing that we are trying to do is study the very, very early universe. So, the most distant galaxies. We just got a big chunk of data at the end of April that we’re kind of analyzing right now. But we already have sort of candidate objects that are very distant. And so, we want to study not only how many of them there are and what their properties are, but how they’re spatially distributed. If they’re kind of grouped together, or if they’re more kind of spread out. And so that’s, I think, something unique we’ll be able to do, we’ll be able to have so many of them. The other thing, that’s a huge benefit there is that if anything is really rare, you know, like, it’s extremely bright. And there might only be, you know, one and a certain patch of the sky, we’re more likely to find those rare things, because we’re covering a large area.

Zehra
And also because it’s different from the previously done studies and like different telescopes?

Jeyhan
Right, exactly. So, we can see things that are much fainter, and therefore, much further away. We can also see things in more detail. So, you know, from Hubble, sort of the extreme things that were found that are very distant, they’re just tiny little smudges, you know, like, you can’t see any detail there. You just like, oh, there’s something there. It’s like a tiny dot. But now we can see structure. And that tells us more information about what’s happening in the galaxies.

Zehra
Like generally, with your whole work and research, have you encountered something that was really surprising or maybe unexpected?

Jeyhan
I guess there’s a few things that have been surprising. One is that so far, people have been finding more galaxies at these great distances than was expected. Like we all made predictions. Because we hadn’t seen them yet. And there’s theoretical predictions for what there might be. And so far, it seems like we’re seeing more things than people predicted, which is kind of fun, because that gives us more to work with. And it’s it was kind of unexpected. And now people are trying to figure out why that is. And so that kind of goes back to the theorists to figure out, you know, what is different about the universe, that there’s more things. So that’s been one surprise.

I guess another surprise, you know, from other surveys I’ve been working with is that there’s a lot of active black holes in these galaxies, like more and more of them than we might have. And maybe we should have known that, I don’t know. But to find so many of them, it’s been kind of exciting. So, it’s been an interesting thing that I think we weren’t really expecting to spend so much time on but it’s been popping up.

Zehra
What would you say is your expectation of the coming years when it comes to this field?

Jeyhan
We’re gonna learn so much. It’s still been less than a year since we started getting data. And there’s already been so much work, and so many papers, and so many discoveries. And it’s like, we only just scratching the surface. So, it’s going to be really exciting to see what comes out.

Zehra
Since you started working for JWST, what would you say was the most exciting thing that you were looking forward to in the beginning and what would you say is it now? Or how did that change their expectation, or your motivation also?

Jeyhan
I think we all kind of had an idea of what to expect based on simulations and what things would look like, but seeing the reality was just kind of mind blowing. Right? And the fact that everything worked. You know, just whenever you have such a big project, so many moving parts, so many things could go wrong, I think, of course, we all hoped nothing catastrophic would go wrong, but little things, little things can go wrong, like, oh, this particular thing doesn’t work, or oh, this instrument is not as sensitive as we thought it would be. But everything was so smooth and went so well. And that just almost never happened. So that was a huge shock.

Zehra
That was a lot of hard work and also good luck, I guess.

Jeyhan
Yeah. And, and because of the delays, the delays helped. Because you test something, it doesn’t work, you’re like, okay, we’re not gonna launch. Well, it doesn’t work, we need to keep testing and fix all the things. So that’s a good thing about the process, even though it made it take longer.

Zehra
So basically, there was like an extra six months to improve on the things and make it work better than I guess.

Jeyhan
And then of course, seeing the data was pretty amazing. Especially the spectra I think most people see images in pictures, and that I think people can relate to that. Spectra don’t mean anything to most people in the public. But, you know, for the scientists looking at spectra, that’s where you’re seeing, like the real physical information, and you can actually see your signatures of the different elements that you’re observing. And, and that’s really cool. And so, like when they did that big press event last summer, and they showed all the different things, they showed a spectrum of a galaxy, it was really far away. So, it’s just a bunch of lines. It probably looked really boring but that was the thing that kind of made me go, oh my God, that looks so cool. Because it’s still crazy to me that we can see that kind of detail at these at these crazy distances.

I think the biggest thing, to me is just the amount of awe and wonder about the universe that a telescope like this conveys. And I think that’s important for all of humanity, right? Even if you don’t know all the details about the science or how things work, just to see like the incredible wonders that are in our universe that we can actually learn about is like one of the biggest achievements of humanity, I think.

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Zehra
We hope you enjoyed our episode. Please visit Longitude [dot] site for the transcript.

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