UCLA and the JWST Revolution
Exactly 100 years ago, in 1924, Edwin Hubble used state-of-the-art telescopes to make one of the most groundbreaking discoveries in the history of astronomy. Our galaxy was not alone but just one of billions, if not trillions, of other galaxies in what we now call the universe. Like Galileo before him, Hubble had changed humanity’s perspective on the cosmos. Now, a new telescope is helping to do that all over again.
NASA’s James Webb Space Telescope (JWST) is the most advanced telescope ever built. Sitting out in space 1.5 million kilometers from Earth and protected by an advanced sunshield, JWST can look further back in time than ever before. As our universe expands, light waves are stretched out. The oldest light in our universe has been stretched out so much it exists only in the infrared state. Meaning that to look back at the earliest moments of the universe, you have to be able to look at infrared light. And that’s what JWST does better than anything before.
Of course, telescopes are just tools. Like Galileo or Hubble, they need dedicated scientists to use them. There may be no place better suited to the task than UCLA’s department of physics and astronomy; a historical leader in infrared astronomy and instrumentation, with decades of close collaboration with NASA. This new technology, combined with some of UCLA’s most creative and imaginative researchers, is leading to a new understanding of the universe and everything in it – including galaxies, stars, black holes and planets. With that knowledge we may, once again, come to a new understanding of our place in the universe.
Sofía Rojas-Ruiz
LOOKING AT THE PAST TO UNDERSTAND OURSELVES
In a story about understanding the universe as a whole, it may be fitting to begin with Sofía Rojas-Ruiz, a postdoctoral scholar who joined UCLA last year. Rojas-Ruiz, who studies the oldest and most distant galaxies, is interested in how the universe became transparent in the first place. “In the early universe, 13 billion years ago, not many galaxies had formed. The universe was full of neutral hydrogen clouds and you would not have been able to see much of anything,” she says.
By the time it reaches us, light that old has all shifted to the infrared wavelength, meaning that you need a telescope like JWST to get the full picture. Work that was virtually impossible with ground-based telescopes like Keck, Rojas-Ruiz can now do in a matter of minutes. It was the formation of stars, and eventually galaxies, that began to break up these neutral hydrogen clouds. But why and how this happened is still a mystery. According to Rojas-Ruiz, certain things in the universe, like the formation and growth of supermassive black holes at the center of most galaxies, are happening faster than we thought was physically possible. Understanding how these early galaxies and black holes formed and evolved is an important step in explaining the formation and ongoing evolution of our own galaxy.
Matt Hosek
LOOKING AT OURSELVES TO UNDERSTAND THE PAST
And speaking of our own galaxy, other researchers are trying to answer similar questions about how galaxies work by staying closer to home. Matt Hosek, a postdoctoral scholar in the Galactic Center Group, is focused on stars at the center of our own Milky Way galaxy and how they interact with the supermassive black hole at its center.
“If you think of our Galaxy as a city, our solar system is really far out in the suburbs,” he says. “Most of what we know about star formation so far is from studying other suburban systems similar to ours.” The Galactic Center, on the other hand, is more like downtown. Not only is it a lot busier, with many more stars, but even the physics works very differently downtown. How does the physics of star formation change when you subject them to such extreme external conditions?
For Hosek, the value of JWST isn’t its reach, but its sensitivity. If you’ve ever seen some of the older pictures of our galaxy, you might remember that the center looks like a kind of bright blob. But that blob is actually billions upon billions of stars. They are just clustered so close together that they appear as one large light. JWST is allowing Hosek, for the first time, to measure individual low mass stars in that massive cluster and make inferences about their mass and how they formed.
While Rojas-Ruiz is looking at distant galaxies to make inferences about our own, Hosek is doing just the opposite. “When we look at distant galaxies, we can’t always observe individual stars, we’re looking at a blob of light. But we can use models we’ve made from the Milky Way to interpret that blob of light into understanding the underlying properties of the stars in that distant galaxy,” he says.
Anna Ciurlo
HOW DO YOU GET A BLACK HOLE TO EAT?
If Matt Hosek is looking in and around our galaxy’s downtown area, then Anna Ciurlo is at city hall; at the very beating heart of our galaxy studying the supermassive black hole, also known as Sagittarius A*, up close and personal. Ciurlo is hoping to use JWST to answer a pressing question. Namely, why isn’t Sagittarius A* eating?!
Ciurlo is focused on a current theory that most likely has nothing to do with diet restrictions. A black hole “feeds” by swallowing material very near to its center. This is important not just for our understanding of black hole growth itself, but also because black holes are believed to regulate the rate of formation of stars in their host galaxies via the energy released while “feeding.” While Sagittarius A* is eating some, it’s not much compared to other black holes we’ve studied. Ciurlo believes this has to do with the placement of our galaxy’s “circumnuclear disk,” a massive molecular cloud that is near Sagittarius A*. Black holes love molecular clouds like this, they swallow them easily and they make the black holes very active. “I believe our circumnuclear disk is may be prevented from reaching Sagittarius A* by the solar winds generated by the billions of stars at the center of our galaxy,” she says.
Ciurlo will put this theory to the test later this year when she gets access to JWST and its powerfully sensitive tools that allow it to see deeper into the circumnuclear disk than ever before. By using Sagittarius A* to better understand what regulates when and how much central black holes feed, she hopes to help explain what, in turn, regulates the evolution and activity of galaxies.
Matt Malkan
OK BUT WHAT EVEN IS A GALAXY?
Of course, if you want to learn more about galaxies, it helps to have an agreed upon definition of a galaxy in the first place. That is something that professor Matt Malkan is challenging us to think differently about. “We are so biased about what galaxies look like - orderly, clean. But the more we learn about them, thanks to JWST, the more diversity we realize there is,” he says. In fact, many of these distant galaxies are disordered and dynamic messes much more out of equilibrium than we previously thought a galaxy could be.
Malkan is getting this picture, in part, by utilizing JWST’s unparalleled ability to spread out light. A prism takes a beam of light and spreads it out into the individual colors of the spectrum. Think of JWST as a prism, but for infrared light. Looking at the infrared version of a spectrum lets us see something we otherwise couldn’t: the types of gas being illuminated by stars. By using this technique, Malkan is able to tell what distant galaxies are actually made of. This is an important piece of the puzzle in one-day understanding how the universe formed in the first place, at the very beginning of time.
Guido Roberts-Borsani
THE BEGINNING OF TIME
That very-beginning-of-time phase is called the “epoch of reionization” and it’s a time in our universe’s history studied by Guido Roberts-Borsani. When the universe first formed, it was so hot and dense that light and matter were coupled together in a plasmic soup. It was only when the universe expanded and cooled, that light was able to break away from matter. It was shortly after this moment that the first stars and first galaxies formed and bathed the Universe with their remarkable light. It may seem unbelievable to be able to look back that deep into our past, to the first stars and galaxies. But Roberts-Borsani is using novel techniques with JWST to do just that.
“JWST has allowed us to measure things we had only guessed at before,” he says. “One important thing we were able to prove is that galaxies built up their stellar content very rapidly and had a lot of heavy elements (such as Carbon and Oxygen) much earlier than expected.” In other words, by utilizing JWST’s ability to look further back into time using infrared light, Roberts-Borsani is shedding some metaphorical light on the very early stages of galaxy formation. Looking this far back in time is like looking at blueprints for the foundation of a skyscraper. It gives a basic understanding of how the structure that would ultimately become the universe came to be.
Alice Shapley
A UNIFYING PERSPECTIVE
And speaking of our universe, it’s important to remember what this is all about. All this research, whether looking at a single star, a supermassive black hole, or an individual galaxy is ultimately about one thing: understanding the origins and evolution of our universe. Or to put it another way, to understand where all this came from!
For Alice Shapley, it’s important to understand that individual galaxies, no matter how far apart they are, are actually part of one unifying system. That perspective has led her to use JWST for some new approaches. “Galaxies are not isolated,” she says. “They have a measurable effect on their surroundings and understanding how gas flows into and out of galaxies can tell us a lot about how they, and in turn our universe, form.” In other words, it’s important not just to look at the galaxy as a self-contained entity, but as something more.
Shapley does this by using JWST’s powerful spectroscopy to measure how much oxygen and other chemical elements a galaxy has over time. The data she and her team recently collected represents a massive step forward in fidelity to make the measurements needed. By looking at very old galaxies that may one day evolve into something similar to our own, she is developing one of the most detailed chemical analyses of galaxies ever.
Tommaso Treu
WHAT’S THE UNIVERSE MADE OF?
It may be fitting to end this story with the research of Tommaso Treu, the very first UCLA researcher to gain access to JWST with a project called “GLASS-JWST”. His project looked deeper back into time than any of the first researchers using the telescope, which means GLASS-JWST looked further back in time than anything before. And he did this by combining JWST’s immense power and a natural magnifying glass in space.
When light from the deep past travels past distant clusters of galaxies towards Earth, the galaxy cluster bends the light and magnifies it. By positioning these galaxies in the foreground of JWST, Treu actually turned what might otherwise be an impediment to our search into an advantage, with surprising results.
“It was this technique that allowed us to realize these very early galaxies existed in the first place - something that was a total shock to the astronomy community,” he said.
Now, Treu is also using JWST to try and answer a fundamental question about our universe. Namely, that the rate our universe is expanding doesn’t seem to match up with its composition at early times, and the subsequent evolution. His team is now using JWST for a completely new measurement technique to understand if our measurements have simply been off or if there is some as-of-yet undiscovered element of the universe. If that turns out to be true it would mean that JWST and UCLA have, once again, redefined our understanding of, well, everything.
I asked professor Malkan how astronomers deal with the struggle of the big questions they shed light on. Every new generation of telescopes, going all the way back to Galileo, has brought with it a completely new understanding of the universe and our place within it. And that, in turn, has at times brought human problems to go along with the science problems. Each new discovery has made humanity, to some, feel smaller and perhaps less significant. How do we reconcile that with our seemingly innate human need to feel important?
Malkan says that many scientists decide to concentrate on one little thing they can do well and put one foot in front of the other. But you can’t ignore the questions indefinitely.
“Sometimes I’m up late at night and I start wondering about those bigger questions. The first thing that always hits me is ‘man this is a big production’ — bigger than any human mind ever dreamed of,” he says. It makes those questions more pressing, the more you know. For Malkan, the answer is simple. “For any human being who gets a chance to think about these things, and I’m lucky to count myself among them, it is worth doing. Because it’s something we can do. In fact, we can’t NOT do it. Otherwise we wouldn’t be fulfilling our role as humans. This is the heritage of all humanity.”