While recent images from the James Webb Space Telescope have dazzled the public, they’ve left some astronomers in disbelief. Like Elizabeth McGrath, who thought something was wrong with JWST’s images of the galaxies she’s studied for a dozen years and knows so well.
They looked completely different, she said. “It was like I was looking at data that you only get for much closer galaxies.”
McGrath, associate professor of astronomy, quickly realized that nothing was amiss. Nor were “her galaxies” any closer than she’d previously measured. She was just seeing them with unprecedented clarity and detail thanks to NASA’s revolutionary James Webb Space Telescope, orbiting a million miles from Earth.
The telescope, which peers at the universe in infrared light, has only just begun to reveal previously unseen aspects of our cosmos. “It’s going to reshape the way we think about a whole variety of topics in astronomy,” said Dale Kocevski, also an associate professor of astronomy.
Kocevski and McGrath are part of an international team of astronomers receiving data from the JWST during its current initial imaging period. As part of CEERS, the Cosmic Evolution Early Release Science Survey, they’ve been preparing for this moment since 2017, when theirs was one of 13 projects selected as part of NASA’s Early Release Science Program.
Since their first download on July 14, 2022, they’ve spent nearly every waking moment working with JWST data.
“We used to marvel at the Hubble Space Telescope’s resolution and sensitivity. And then all of the sudden, Webb makes it look blurred,” said Kocevski, barely able to contain his excitement. The JWST images are “spectacular. There’s no other way to describe them—they’re fantastic.”
The CEERS team is using JWST to conduct an extragalactic survey, which means they’re looking far beyond our Milky Way galaxy and its local neighbors. In one of the new images, the team discovered what could possibly be the earliest galaxy ever observed. “If the finding is confirmed … its presence would indicate that galaxies started forming much earlier than many astronomers previously thought,” a NASA press release said.
These images will aid Kocevski, McGrath, and the CEERS team in their study of how some of the earliest galaxies formed when the universe was one-tenth of its current age, a mere 290 million years after the Big Bang.
Kocevski and McGrath, a husband-and-wife team, both study galaxy evolution. Kocevski investigates how and why black holes grow at the center of some supermassive galaxies and not in others. McGrath’s work focuses on how galaxies stop forming stars and die and if there’s a correlation between a galaxy’s shape and its star-formation activity. With JWST’s ability to image galaxies so much farther back in time, Kocevski and McGrath can study galaxies from earlier epochs and fill in the cosmic timeline of galaxies’ life spans.
As their research gets underway, Kocevski and McGrath are also fulfilling their commitment as part of the six-month Early Release Science Program to help NASA learn how to process JWST’s data. The telescope transmits raw data—essentially strings of zeros and ones—that’s automatically processed at the Space Telescope Science Institute, which operates JWST for NASA. But McGrath and Kocevski have found the processed data not as clean as it could be, and they’ve had to write computer code to improve it.
One of the problems is the presence of scattered light. Because JWST’s segmented parabolic mirror is so large—21.6 feet (6.5 meters) in diameter—and exposed to space, it detects starlight coming from all directions. Removing the resulting streaks and blotches will make the background black and foreground objects pop.
At the end of the six months, the CEERS team will not only release their final data but the methods they’ve learned. Then they’ll turn their full attention to scientific research—and there’s plenty of it ahead.
As he works, Kocevski makes a list of research ideas. “It just keeps growing,” he said. It’s not just seeing their familiar galaxies anew, but the frontiers coming into focus.
“I think we’re just on the cusp,” said Kocevski. “There’s a whole swath of galaxies the Hubble doesn’t see, hasn’t seen, can’t see. And others we probably haven’t even uncovered yet because we’re still getting the data to a point where we can identify them.”
And it’s not just seeing the galaxies, “but the implications that you draw from all these new objects you didn’t even know existed,” McGrath said.
“There’s all this new science that’s being opened up by JWST that I didn’t even think about before.”
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