This simulation shows how stellar rods (left) and rod-driven gas flows (right) form. Stellar bars play an important role in galactic evolution by channeling gas into the central regions of the galaxy, where it is rapidly converted into new stars, 10 to 100 times faster than the rate in the rest of the galaxy. The bars also indirectly aid the formation of supermassive black holes in the centers of galaxies by directing the gaseous part of the way. Credit: Françoise Combes, Paris Observatory
new photos 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 how stellar rods (left) and rod-driven gas flows (right) form. Stellar bars play an important role in galactic evolution by channeling gas into the central regions of the galaxy, where it is rapidly converted into new stars, 10 to 100 times faster than the rate in the rest of the galaxy. The bars also indirectly aid the formation of supermassive black holes in the centers of galaxies by directing the gaseous part of the way. Credit: Françoise Combes, Paris Observatory
The discovery of bars during these early ages has shaken up scenarios of galaxy evolution in several ways.
“This early detection of the bars means that models of galaxy evolution now have a new path through the bars to accelerate the production of new stars at early ages,” Jogee said.
And the existence of these early bars challenges theoretical models because they need to correct for galactic physics in order to predict the correct abundance of bars. The team will test different models in their upcoming papers.
A montage of JWST images shows six examples of barred galaxies, two of which represent the highest recovery times quantified and characterized to date. The labels at the top left of each number show each galaxy’s retrograde time, which ranges from 8.4 to 11 billion years ago (Gyr), when the universe was a mere 40% to 20% of its current age. Credit: NASA/CEERS/The University of Texas at Austin
JWST can reveal structures in distant galaxies better than Hubble for two reasons: First, its larger mirror gives it greater light-gathering ability, allowing it to see farther and with higher resolution. Second, it can see through the dust better because it observes at longer infrared wavelengths than the Hubble telescope.
Undergraduates Eden Wise and Zilei Chen played a major role in the research by visually reviewing hundreds of galaxies, looking for those that appeared to have bars, which helped narrow the list down to a few dozen so that other researchers could analyze it with more intensive calculations. Approaching.
Reference: “First look at z > 1 Bars in the rest of the near-infrared frame with JWST early CEERS imagery” By Yuchen Guo, Sharda Joji, Stephen L Finkelstein, Zili Chen, Aiden Weiss, Michaela P Bagley, Guillermo Barrow, Stegen & Witts , Dale D. Kosevski, Jehan S. Kartaltepe, Elizabeth J. McGrath, Henry C. Ferguson, Bahram Mobacher, Mauro Giavalescu, Ray A. Lucas, George A. Zavala, Jennifer M. Lutz, Norman A. Grojean, Mark Huertas-Company, Jesus 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 G. Cleary, Rosemary T. Cogan, MC Cooper, Luca Constantin, Darren Croton, Kelsey Davis, Alexandre de la Vega, Avishai Dekel, Maximilian Franco, Jonathan P. Gardner, Ben W. Holwerda, Taylor A. Hutchison, Viraj Pandya, Pablo G. Perez-Gonzalez, Swara Ravindranath, Caitlin Rose, Jonathan R. Trump, Weichen Wang Accepted, Astrophysical Journal Letters.
arXiv: 2210.08658
Other co-authors from the University of Austin are Stephen Finkelstein, Michaela Bagley, and Maximilian Franco. Dozens of co-authors from other institutions hail from the United States, the United Kingdom, Japan, Spain, France, Italy, Australia, and Israel.
Funding for this research was provided in part by the Roland K. Blumberg Endowment in Astronomy, the Heising-Simons Foundation, and NASA. This work drew on resources at the Texas Center for Advanced Computing, including Frontera, the most powerful supercomputer at an American university.
