33 Billion Light Years Away: Webb Space Telescope Finds Galaxies That Challenge

Insights Into Early Universe

Because the light from these galaxies had to travel for so long to reach Earth, it provides a window into the past. The research team estimates that the light detected by JWST was emitted by the two galaxies when the universe was about 330 million years old and traveled for about 13.4 billion light years to reach the JWST. But, the researchers said, the galaxies are currently closer to 33 billion light years away from Earth due to the expansion of the universe over this time.

“The light from these galaxies is ancient, about three times older than the Earth,” said Joel Leja, assistant professor of astronomy and astrophysics at Penn State and a member of UNCOVER. “These early galaxies are like beacons, with light bursting through the very thin hydrogen gas that made up the early universe. It is only by their light that we can begin to understand the exotic physics that governed the galaxy near the cosmic dawn.”

Using the James Webb Space Telescope, scientists have found two distant galaxies in Pandora’s Cluster, providing new insights into the early universe. These galaxies, unique in size and appearance, challenge our understanding of galaxy formation in the cosmos’ infancy. Credit: NASA

Notably, the two galaxies are considerably larger than the three galaxies previously located at these extreme distances. One is at least six times larger at about 2,000 light-years across. For comparison, the

“Previously discovered galaxies at these distances are point sources — they appear as a dot in our images,” Wang said. “But one of ours appears elongated, almost like a peanut, and the other looks like a fluffy ball. It is unclear if the difference in size is due to how the stars formed or what happened to them after they formed, but the diversity in the galaxy properties is really interesting. These early galaxies are expected to have formed out of similar materials, but already they are showing signs of being very different than one another.”

Research Methodology

The two galaxies were among 60,000 sources of light in Pandora’s Cluster detected in one of JWST’s first deep field images taken during 2022, its first year of science operations. This region of space was selected in part because it is located behind several galaxy clusters that create a natural magnification effect called gravitational lensing. The gravitational pull of the clusters’ combined mass warps the space around it, focusing and magnifying any light that passes nearby and providing a magnified view behind the clusters.

In a matter of months, the UNCOVER team narrowed down the 60,000 light sources to 700 candidates for follow up study, eight of which they thought could potentially be among the first galaxies. Then, JWST again pointed at Pandora’s Cluster, recording the candidates’ spectra — a sort of fingerprint detailing the amount of light given off at each wavelength.

“Several different teams are using different approaches to look for these ancient galaxies, and each have their strengths and weaknesses,” Leja said. “The fact that we’re pointing at this giant magnifying lens in space gives us an incredibly deep window, but it’s a very small window so we were rolling the dice. Several of the candidates were inconclusive, and at least one was a case of mistaken identity — it was something much closer that mimics a distant galaxy. But we were lucky, and two turned out to be these ancient galaxies. It’s incredible.”

Properties and Implications

The researchers also used detailed models to infer the properties of these early galaxies when they emitted the light detected by JWST. As the researchers expected, the two galaxies were young, had few metals in their composition, and were growing rapidly and actively forming stars.

“The first elements were forged in the cores of early stars through the process of fusion,” Leja said. “It makes sense that these early galaxies don’t have heavy elements like metals because they were some of the first factories to build those heavy elements. And, of course, they would have to be young and star-forming to be the first galaxies, but confirming these properties is an important basic test of our models and helps confirm the whole paradigm of the

This work was the result of a successful proposal submitted to NASA suggesting how to use JWST during its first year of science operations. In the first three cycles of submissions, NASA received four to ten times more proposals than available observing time on the telescope would allow and had to select only a fraction of those proposals.

“Our team was very excited and a little surprised when our proposal was accepted,” Leja said. “It involved coordination, quick human action, and the telescope pointing at the same thing twice, which is a lot to ask of a telescope in its first year. There was a lot of pressure because we only had a few months to determine the objects for follow up. But JWST was built for finding these first galaxies, and it’s so exciting to be doing that now.”

Reference: “UNCOVER: Illuminating the Early Universe—JWST/NIRSpec Confirmation of z > 12 Galaxies” by Bingjie Wang, 冰洁 王, Seiji Fujimoto, Ivo Labbé, Lukas J. Furtak, Tim B. Miller, David J. Setton, Adi Zitrin, Hakim Atek, Rachel Bezanson, Gabriel Brammer, Joel Leja, Pascal A. Oesch, Sedona H. Price, Iryna Chemerynska, Sam E. Cutler, Pratika Dayal, Pieter van Dokkum, Andy D. Goulding, Jenny E. Greene, Y. Fudamoto, Gourav Khullar, Vasily Kokorev, Danilo Marchesini, Richard Pan, John R. Weaver, Katherine E. Whitaker and Christina C. Williams, 13 November 2023, The Astrophysical Journal Letters.
DOI: 10.3847/2041-8213/acfe07

In addition to Penn State, the team includes researchers from the University of Texas Austin, the Swinburne University of Technology in Australia, Ben-Gurion University of the Negev in Israel,

This work was supported by NASA, the United States-Israel Binational Science Foundation, the U.S. National Science Foundation, the Israel Ministry of Science & Technology, the French National Centre for Space Studies, the French National Institute for Earth Sciences and Astronomy, the Research Corporation for Scientific Advancement, the Dutch Research Council, the European Commission’s and University of Groningen’s CO-FUND Rosalind Franklin program, the National Astronomical Observatory of Japan and the NOIR Lab.