James Webb Space Telescope spies Milky Way mimics that could challenge theories of galaxy evolution

Montage of JWST images showing six example barred galaxies, two of which represent the highest lookback times quantitatively identified and characterized to date. The labels in the top left of each figure show the lookback time of each galaxy, ranging from 8.4 to 11 billion years ago (Gyr), when the universe was a mere 40% to 20% of its present age.
Montage of JWST images showing six example barred galaxies, two of which represent the highest lookback times quantitatively identified and characterized to date. The labels in the top left of each figure show the lookback time of each galaxy, ranging from 8.4 to 11 billion years ago (Gyr), when the universe was a mere 40% to 20% of its present age. (Image credit: NASA/CEERS/University of Texas at Austin)

James Webb Space Telescope keeps surprising us.

A key advantage of the James Webb Space Telescope (JWST) is its ability to peer deep into the past. By looking in the infrared part of the electromagnetic spectrum, it's able to see light that has taken billions of years to reach us, stretched out by the expanding universe along its journey.

JWST's specialized eyes on the universe recently revealed yet another surprise —multiple galaxies that look like our Milky Way, but from between 8 and 11 billion years in the past when the universe was much younger. 

New research described in a statement from UT Austin (opens in new tab) presents observations from the JWST Cosmic Evolution Early Release Science Survey (opens in new tab) showing galaxies with stellar bars, straight lines of stars stretching from galactic centers to their outer disks, at this time in the young universe. The discovery could "require scientists to refine their theories of galaxy evolution," according to the statement.

Related: 12 amazing James Webb Space Telescope discoveries of 2022

"I took one look at these data, and I said, 'We are dropping everything else!'" Shardha Jogee, an astronomer at UT Austin, said in the statement.

This is the first time stellar bars have been observed in such young galaxies, challenging existing models of how galaxies form and grow. They may also help astronomers answer existing questions about galaxies, such as how supermassive black holes in galactic centers grow and how galaxies get enough material to make stars in their centers, known as the supply chain problem.

"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," added lead author Yuchen Guo. "So everything is new. It's like going into a forest that nobody has ever gone into."

Jogee added that these stellar bars could "solve the supply chain problem in galaxies."

"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," Jogee explained.

This discovery is yet another testament to the extraordinary capabilities of NASA's new workhorse space telescope, and a step towards understanding how galaxies like our Milky Way came to be.

The research is published in The Astrophysical Journal Letters (opens in new tab).

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Briley Lewis
Space.com contributor

Briley Lewis (she/her) is a freelance science writer and Ph.D. Candidate/NSF Fellow at the University of California, Los Angeles studying Astronomy & Astrophysics. Follow her on Twitter @briles_34 (opens in new tab) or visit her website www.briley-lewis.com (opens in new tab)

  • rod
    JWST seems to show objects that are causing some viewers, headaches :) I note from the paper published for this report.

    ref - First Look at z > 1 Bars in the Rest-Frame Near-Infrared with JWST Early CEERS Imaging, https://arxiv.org/abs/2210.08658, 12-Dec-2022.

    "Stellar bars are key drivers of secular evolution in galaxies and can be effectively studied using rest-frame near-infrared (NIR) images, which trace the underlying stellar mass and are less impacted by dust and star formation than rest-frame UV or optical images. We leverage the power of JWST CEERS NIRCam images to present the first quantitative identification and characterization of stellar bars at z>1 based on rest-frame NIR F444W images of high resolution (~1.3 kpc at z ~ 1-3). We identify stellar bars in these images using quantitative criteria based on ellipse fits. For this pilot study, we present six examples of robustly identified bars at z>1 with spectroscopic redshifts, including the two highest redshift bars at ~2.136 and 2.312 quantitatively identified and characterized to date. The stellar bars at z ~ 1.1-2.3 presented in our study have projected semi-major axes of ~2.9-4.3 kpc and projected ellipticities of ~0.41-0.53 in the rest-frame NIR. The barred host galaxies have stellar masses ~ 1×10^10 to 2×10^11 M⊙, star formation rates of ~ 21-295 M⊙ yr^−1, and several have potential nearby companions. Our finding of bars at z ~1.1-2.3 demonstrates the early onset of such instabilities and supports simulations where bars form early in massive dynamically cold disks. It also suggests that if these bars at lookback times of 8-10 Gyr survive out to present epochs, bar-driven secular processes may operate over a long time and have a significant impact on some galaxies by z ~ 0."

    My observation. The March issue of Sky & Telescope has a report on spiral galaxies. "14 Where Do Spirals Come From? Spiral galaxies are ubiquitous in the nearby universe, yet we still don’t know how their patterns arise." "By Monica Young" It seems the need for recycling spiral arms over billions of years is acute and density waves must recreate spiral arms regularly, but they will look different too at different ages. However, spiral galaxies as seen by JWST out to 11 billion light years, is well beyond *nearby*. Using cosmology calculators, z=3.0 is about 11.5 Gly distance. Trouble here in BB cosmology? I note another report from concerning JWST spiral galaxies seen too.

  • billslugg
    Reading about spiral galaxies I was surprised to find that the arms are not groups of stars that travel together. They are density waves, like traffic slowdowns. At some particular radius, called the "corotation radius" the stars and the arms rotate at the same angular velocity. Outside that radius the arms travel faster than the stars, inside that radius the stars travel faster than the arms.
    I hazard a guess the formation of arms is the result of two competing forces, just as traffic slowdowns are. In traffic, people are far quicker to slow down when they start closing the gap with the car in front of them than they are to speed up once the gap opens.
    I can't hazard a guess how that occurs in galaxies though.