It is turning out to be a month of more discoveries for the James Webb Space Telescope (JWST). Earlier this month, a research team from UC Riverside found a Milky Way-type galaxy in the early universe. Now, an international team led by Penn State researchers have discovered the second- and fourth-most distant galaxies ever observed in a region of space known as Pandora’s Cluster, or Abell 2744, using data from JWST.
Following up on a deep field image of the area, the team confirmed the distance of these ancient galaxies and inferred their properties using new spectroscopic data — information about light emitted across the electromagnetic spectrum — from JWST. At nearly 33 billion light years away, these incredibly distant galaxies offer insights into how the earliest galaxies might have formed, a press release explains.
The findings were described in a paper published on 13 November in the journal Astrophysical Journal Letters.
Researchers say that unlike other galaxies confirmed at this distance that appear in images as red dots, the new galaxies are larger and appear like a peanut and a fluffy ball. “Very little is known about the early universe, and the only way to learn about that time and to test our theories of early galaxy formation and growth is with these very distant galaxies,” said first-author Bingjie Wang, postdoctoral scholar in the Penn State Eberly College of Science and a member of the JWST UNCOVER (Ultradeep NIRSpec and NIRCam ObserVations before the Epoch of Reionization) team that conducted the research. “Prior to our analysis, we knew of only three galaxies confirmed at around this extreme distance. Studying these new galaxies and their properties has revealed the diversity of galaxies in the early universe and how much there is to be learned from them,” Wang explains in the release.
Further, 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 say in the release -- 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,” Joel Leja, assistant professor of astronomy and astrophysics at Penn State and a member of UNCOVER says in the release. “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.”
Interestingly, 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 Milky Way is approximately 100,000 light years across, but, Wang said, the early universe is thought to have been very compressed, so it’s surprising that the galaxy is as large as it is," the release explains.
The James Webb Space Telescope, launched in December 2021 by US space agency Nasa in collaboration with other space agencies, is a large infrared telescope with an approximately 6.5-meter primary mirror. Nasa calls JWST “the premier observatory of the next decade”, which is serving thousands of astronomers worldwide. “It studies every phase in the history of our Universe, ranging from the first luminous glows after the Big Bang, to the formation of solar systems capable of supporting life on planets like Earth, to the evolution of our own Solar System,” JWST’s official website explains.