For the first time, the latest images from NASA’s James Webb Space Telescope (JWST) show bar galaxies – which are elongated structures of stars stretching from the middle of galaxies to their outer disks – when the universe was only 25% of what it is today your age
JWST’s power to map galaxies at high resolution and at longer infrared wavelengths than Hubble allows it to peer through dust and reveal the underlying structure and mass of distant galaxies. This can be seen in these two images of the galaxy EGS23205, seen as it was about 11 billion years ago. In the HST image (left, taken in the near-infrared filter), the galaxy is little more than a disc-like blob obscured by dust and affected by the glow of young stars, but in the corresponding JWST mid-infrared image (taken last summer), it’s a beautiful spiral galaxy with clear star band. Image credit: NASA/CEERS/University of Texas at Austin
The discovery of these galaxies with barriers identical to the Milky Way so early in the universe will lead astrophysicists to improve their theories of galaxy evolution.
Before JWST, images from the Hubble Space Telescope had never sensed bands of these young epochs. In the Hubble image, one galaxy, EGS-23205, is just above a disc blob, but in the corresponding JWST image taken last summer, it is a magnificent spiral galaxy with a clear star bar.
“I looked at this data and said, ‘We’re throwing everything else away!'” said Sharda Joji, a professor of astronomy at the University of Texas at Austin. “Bands barely visible in the Hubble data just popped up in the JWST image, showing the tremendous power of JWST to see the underlying structure in galaxies,” she said, explaining the data from the Cosmic Evolutionary Early Release Survey (CEERS ), led by Steven Finkelstein, UT Austin professor.
The research team also found another barred galaxy, EGS-24268, from around 11 billion years ago, making two barred galaxies present further back in time than anything previously discovered.
The researchers highlight these two galaxies and present examples of four other barred galaxies from more than 8 billion years ago. This article was published in The Astrophysical Journal Letters.
For this study, we are looking at a new regime where no one has used this kind of data or done this kind of quantitative analysis before. So everything is new. It’s like going into a forest where no one has ever been before.
Yuchen “Kay” Guo, lead study author and graduate student, University of Texas at Austin
By directing gas into the intermediate regions and promoting star formation, lattices play a critical role in galaxy evolution.
Bars solve the galactic supply chain problem. Just as we must bring raw material from the harbor to the inland factories that make new products, the bar powerfully transports gas into the central region, where the gas rapidly turns into new stars at a rate typically 10 to 100 times faster than in the rest of the the galaxy.
Sharda Joji, Professor of Astronomy, University of Texas at Austin
The lattices also aid the growth of supermassive black holes in the centers of galaxies by channeling the gas part of the way.
“This discovery of early bars means that models of galaxy evolution now have a new path through bars to accelerate the production of new stars at early epochs,” Jogi added.
JWST can reveal features in more distant galaxies better than Hubble for two reasons: First, its larger mirror offers greater light-gathering capacity, allowing it to look farther and with better resolution . Second, it can observe past dust better because it operates at longer infrared wavelengths than Hubble.
Students Eden Wise and Zilei Chen played an important role in the study, visually analyzing hundreds of galaxies in search of those that appeared to have bars, which helped narrow the list down to a few dozen so other scientists could study them with more focused mathematical method.
Steven Finkelstein, Michaela Bagley and Maximilien Franco are other co-authors from UT Austin. Several other co-authors from other institutions come from the US, UK, Japan, Spain, France, Italy, Australia and Israel.
The Roland K. Blumberg Foundation in Astronomy, the Heising-Simons Foundation, and NASA provided funding for this study in part. This research depended on resources at the Texas Advanced Computing Center, along with Frontera, the most powerful supercomputer at an American university.
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