As NASA released the first public images from the James Webb Space Telescope in July, Anthony Gonzalez and Desika Narayanan were eagerly awaiting their own download from the advanced satellite.
Professors of Astronomy at UF, Narayanan and Gonzalez are part of the Early Release Science program, those investigators with high-priority research programs who have been given access to the first data coming from the telescope. In this prized position, the collaborators are committed to sharing their work as they go and developing tools to help future researchers analyze the data.
“The goal of the program is really to understand star formation at early times in the universe,” said Gonzalez. “This then leads to bigger question of how do galaxies form and change over time. We’re trying to look at progenitors of galaxies that might one day become like the Milky Way.”
To study the early universe, astronomers must find distant objects, which we see as they were billions of years ago. To see that far away, they use the universe’s largest magnifying lens.
“Just as you can magnify light with a glass lens, you can magnify light with very large masses,” said Gonzalez. The team is studying four glaxies that are magnified 10 to 40 times their size by this gravitational lensing effect, helping them see more distant objects up close.
These early stars and galaxies permanently changed the universe by producing brand new elements, including those that allowed life to form.
“As the universe evolves, and star formation keeps happening and stars explode, you start to get more and more heavy elements until you get to today, where you have super heavy elements, even uranium,” explained Narayanan. This increasing abundance of heavy elements drives the evolution of galaxies from shortly after the Big Bang to what we see today.
Gonzalez and Narayanan are extending the models of this galactic evolution back to the earliest galaxies. Scientists measure the elemental composition of galaxies by looking at the signatures these elements leave in the light coming from those galaxies. These methods work well for nearby galaxies.
“But nobody knows if these methods work for early universe galaxies,” said Narayanan. “For all this time, we've only had theoretical models. We've never had observational data. And now, for the first time, we're going to start to get a sense of how the chemical evolution of galaxies has evolved through the dawn of time.”
Astronomers have it tough, says Jaehan Bae, a professor of astronomy at UF. They can’t set up experiments of galaxies crashing into one another or supernovas exploding. To answer how the universe works, astronomers have to look for natural experiments in the night sky.
For Bae, who studies the formation of planets, that means finding baby planets as they’re just coming together. “The best way to do this is to observe planets that are still forming somewhere else in the universe. This has become possible in the last few years thanks to the increasing capability of observing facilities,” Bae said.
In recent years, Bae’s team has used ground-based observatories to discover indirect evidence of planets forming in the disks of material that surround young stars. But the best analysis would come from a clear image of infrared wavelengths, the kind of heat signatures that Earth’s atmosphere interferes with – but that the JWST excels in capturing from space.
“What we really need is the direct image of those planets. It’s really challenging to do that from a ground-based telescope,” Bae said. “That’s where James Webb will be really helpful. We can look at these planets in infrared wavelengths.”
Just a couple decades ago, humanity first learned that other stars have their own planets. Today, the number of confirmed exoplanets — those orbiting stars other than our own — is in the thousands. As the James Webb Space Telescope prepares to survey countless more, the question on everyone’s mind is: Do these other worlds harbor life?
“It’s a question of finding life and recognizing it,” said Katia Matcheva, a UF professor of physics. When the planets are a thousand light years away, that’s no easy feat.
To help in the effort, Matcheva’s team is developing improved models to analyze the light that passes by exoplanets as they transit in front of their stars. “If the planet has an atmosphere, you can get an imprint of the chemical composition of the planet,” said Matcheva. Signs of water, oxygen or other life-supporting molecules could mean that life took hold on these exoplanets. But scientists are still puzzling out what would qualify as a clear signature of alien life in the data.
The JWST’s work in infrared is ideal for studying planetary atmospheres. But with so much high-quality data pouring in, the problem will become analyzing it all. So Matcheva and her collaborator Konstantin Matchev are preparing machine-learning systems to assist in deciphering this avalanche of data so scientists can be more confident in identifying unambiguous signs of life — if it’s out there.
As Adam Ginsburg began studying astronomy, he discovered that most of the big questions he wanted to answer about the cosmos came down to one unsolved riddle: Why are big stars big and small stars small?
“Every question I asked, no matter what it was, all pointed back to this fundamental problem,” said Ginsburg, a professor of astronomy at UF.
The JWST is providing Ginsburg and his team their best chance yet to solve this unanswered question, known in astronomy as the initial mass function.
“We’re trying to figure out how stars form,” said Ginsburg. “To study this, we’re looking at the center of our galaxy. It’s a special place because it has a lot more stars around, a lot more gas around”
His research group is turning the telescope on a busy cloud of gas near the center of the galaxy jokingly called “the brick” because it is so difficult to see through. But thanks to the telescope’s work in infrared wavelengths, Ginsburg will get to peer inside the thick gas to search for young stars. By catching stars that are still growing, Ginsburg can start to answer why they grow to the sizes that they do, putting the puzzle pieces into place to answer deeper questions about our universe.
Imagine a small city that manages to pack in the mass of the entire sun.
That’s what life is like for neutron stars, the most extreme cosmic objects short of black holes. Neutron stars form from the husks of a dying star that collapses under its own immense gravity. Occasionally, two neutron stars collide, and the resulting explosion creates a smorgasbord of new elements.
“We know now that the collision of these neutron stars is likely responsible for most of the heavy elements we can find in the universe and on Earth itself,” said Imre Bartos, a professor of physics at UF. “These are very important cosmic events. However, we still have very limited information about how this process unfolds.”
Bartos is a member of the LIGO gravitational-wave observatory. LIGO uses hyper-accurate lasers and mirrors to detect ripples in spacetime when massive objects like neutron stars and black holes collide. But what LIGO can’t see is light. That’s where the James Webb Space Telescope comes in.
“The process of creating these heavy elements has its signature in infrared light. The James Webb telescope is almost custom-made to observe these events,” Bartos said.
By combining observations of gravitational waves and infrared light from the telescope, Bartos hopes to come away with a clearer understanding of how the universe seeded itself with the heaviest elements — gold, platinum, uranium — that enrich life on Earth.
At the center of every galaxy, including the Milky Way, sits a supermassive black hole, which might reach a billion times the mass of the sun. Laura Blecha, a professor of physics at UF, is trying to understand how these behemoths form and evolve over billions of years.
How do you study an object famous for its ability to let nothing, not even light, escape? Look for the swirl of gas energized by intense gravity as it falls into the void.
“JWST, because it has much better sensitivity, and it's going to be able to observe things at very early times in the universe, is going to be good for detecting the signals from the fainter black holes,” Blecha said. “So that's going to help us understand a lot more about how these black holes form and grow.”
Blecha is developing models that can simulate the different possible ways the earliest of these supermassive black holes might have formed. Data from James Webb could help determine which of these models of the early universe is correct.
The new telescope’s infrared vision will also help Blecha study the changes that occur when two galaxies, and their central black holes, merge together.
“There's evidence that some of these systems have black holes that are going through rapid periods of growth,” Blecha said. “All that chaos creates a lot of dust in the center of the galaxy that obscures light coming from the accreting black hole. Because JWST sees it in infrared, it can see through that dust better and give us a look inside.”
In astronomy, distance is everything. It’s also incredibly difficult to come by.
An object in the night sky could be dim and nearby or bright and far away. Within the Milky Way, some straightforward geometry might be all you need to tell the difference. But for “way, way out there,” you need something better.
Enter supernovas. The deaths of stars much more massive than our sun are always marked by these extraordinary celestial explosions. But under very special circumstances, a star the size of our sun can also lead to such a fantastic display of energy, called a Type 1a supernova, resulting from the overflow of matter from a close companion star.
“When they explode, it seems to be the case that they all reach the same peak in luminosity and drop off in brightness at the same rate,” said Charles Telesco, a professor of astronomy at UF. Referred to as standard candles, the consistent luminosity of these explosions makes their distance much easier to measure. “We can use them to measure the expansion of the universe at that distance.”
Telesco specializes in designing and constructing astrophysical detector systems. He got into supernovas when an instrument that he and his UF team designed for UF's telescope in Spain — tuned to just the right kind of infrared light — captured in fine detail a nearby supernova.
Now working with the latest infrared observatory, the James Webb Space Telescope, Telesco is part of a team that will monitor Type 1a supernovas to understand their nature and test assumptions that scientists have relied on to determine that the universe is expanding at an accelerating rate.
“We want to be able to characterize these standard candles better and to know if there are corrections that need to be made to our observations,” Telesco said.