This simulation shows both how a stellar bar forms (left) and gas influx by the bar (right). Stellar bars play an important role in the evolution of galaxies by injecting gas into the galaxy’s central region. The gas is rapidly transformed into new stars at rates typically 10 to 100 times faster than the rest of the galaxy. Bars also indirectly help grow supermassive black holes at the center of galaxies by flowing gas along the way.Credit: Francoise Combes, Paris Observatory
new images from[{” attribute=””>NASA’s James Webb Space Telescope (JWST) reveal for the first time galaxies with stellar bars — elongated features of stars stretching from the centers of galaxies into their outer disks — at a time when the universe was a mere 25% of its present age. The finding of so-called barred galaxies, similar to our Milky Way, this early in the universe will require astrophysicists to refine their theories of galaxy evolution.
Prior to JWST, images from the Hubble Space Telescope had never detected bars at such young epochs. In a Hubble image, one galaxy, EGS-23205, is little more than a disk-shaped smudge, but in the corresponding JWST image taken this past summer, it’s a beautiful spiral galaxy with a clear stellar bar.
“I took one look at these data, and I said, ‘We are dropping everything else!’” said Shardha Jogee, professor of astronomy at The University of Texas at Austin. “The bars hardly visible in Hubble data just popped out in the JWST image, showing the tremendous power of JWST to see the underlying structure in galaxies,” she said, describing data from the Cosmic Evolution Early Release Science Survey (CEERS), led by UT Austin professor, Steven Finkelstein.
The power of JWST to map galaxies at high resolution and at longer infrared wavelengths than Hubble allows it look through dust and unveil 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 disk-shaped smudge obscured by dust and impacted by the glare of young stars, but in the corresponding JWST mid-infrared image (taken this past summer), it’s a beautiful spiral galaxy with a clear stellar bar. Credit: NASA/CEERS/University of Texas at Austin
The team identified another barred galaxy, EGS-24268, also from about 11 billion years ago, which makes two barred galaxies existing farther back in time than any previously discovered.
In an article accepted for publication in The Astrophysical Journal Letters, they highlight these two galaxies and show examples of four other barred galaxies from more than 8 billion years ago.
“For this study, we are looking at a new regime where no one had used this kind of data or done this kind of quantitative analysis before,” said Yuchen “Kay” Guo, a graduate student who led the analysis, “so everything is new. It’s like going into a forest that nobody has ever gone into.”
Bars play an important role in galaxy evolution by funneling gas into the central regions, boosting star formation.
“Bars solve the supply chain problem in galaxies,” Jogee said. “Just like we need to bring raw material from the harbor to inland factories that make new products, a bar powerfully transports gas into the central region where the gas is rapidly converted into new stars at a rate typically 10 to 100 times faster than in the rest of the galaxy.”
Bars also help to grow supermassive black holes in the centers of galaxies by channeling the gas part of the way.
This simulation shows both how a stellar bar forms (left) and gas influx by the bar (right). Stellar bars play an important role in the evolution of galaxies by injecting gas into the galaxy’s central region. The gas is rapidly transformed into new stars at rates typically 10 to 100 times faster than the rest of the galaxy. Bars also indirectly help grow supermassive black holes at the center of galaxies by flowing gas along the way.Credit: Francoise Combes, Paris Observatory
The discovery of bars in such an early epoch shakes up the galactic evolutionary scenario in several ways.
“The discovery of this early bar means that galaxy evolution models now have a new pathway through the bar to accelerate new star formation in early epochs,” said Jogee.
And the very existence of these early bars challenges theoretical models, as the physics of the galaxy needs to be correctly understood in order to predict the correct amount of bars. I plan to test the model.
A montage of JWST images showing six example bar galaxies. His two of them represent the longest lookback times quantitatively identified and characterized to date. The labels in the upper left of each figure show the retrospective time of each galaxy from 8.4 to 11 billion years ago (Gyr), when the Universe was only 40% to 20% of its present age.Credit: NASA/CEERS/University of Texas at Austin
There are two reasons why JWST can reveal the structure of distant galaxies better than Hubble. First, the larger the mirror, the more light it collects, allowing you to see farther and with higher resolution. Second, it observes at longer infrared wavelengths than Hubble, so it can see well through dust.
Undergraduates Eden Wise and Zilei Chen played key roles in this research. We visually checked hundreds of galaxies, looking for galaxies that appeared to have bars. This allowed us to narrow the list down to a few dozen for other researchers to analyze with more intensive mathematical techniques. approach.
References: Yuchen Guo, Shardha Jogee, Steven L. Finkelstein, Zilei Chen, Eden Wise, Micaela B. Bagley, Guillermo Barro, Stijn Wuyts, Dale D. Kocevski, Jeyhan S. Kartaltepe, Elizabeth J. McGrath, Henry C. Ferguson , Bahram Mobasher, Mauro Giavalisco, Ray A. Lucas, Jorge A. Zavala, Jennifer M. Lotz, Norman A. Grogin, Marc Huertas-Company, Jesús Vega-Ferrero, Nimish P. Hathi, Pablo Arrabal Haro, Mark Dickinson, Anton M. Koekemoer, Casey Papovich, Nor Pirzkal, LY Aaron Yung, Bren E. Backhaus, Eric F. Bell, Antonello Calabrò, Nikko J. Cleri, Rosemary T. Coogan, MC Cooper, Luca Costantin, Darren Croton, Kelsey Davis, Alexander de la Vega, Avishai Dekel, Maximilian Franco, Jonathan P. Gardner, Bennu W. Horwada, Taylor A. Hutchison, Viraj Pandia, Pablo G. Pérez-González, Swara Ravindranath, Caitlin Rose, Jonathan R. Trump and Weichen Wang accept and Astrophysics Journal Letter.
arXiv:2210.08658
Other co-authors of UT Austin are Steven Finkelstein, Micaela Bagley, and Maximilian Franco. There are dozens of co-authors from other institutions in the US, UK, Japan, Spain, France, Italy, Australia and Israel.
Funding for this research was provided in part by the Roland K. Blumberg Astronomy Foundation, the Heising-Simons Foundation, and NASA. The work relied on the resources of the Texas Advanced Computing Center, which includes Frontera, the most powerful supercomputer at any US university.
