Astronomers say infrared readings from NASA’s James Webb Space Telescope have revealed a new record-holder for the most distant galaxy observed in the universe — a smudge of stars whose light started its journey a mere 290 million years after the big bang.
The galaxy, known as JADES-GS-z14-0, dethroned the previous champion, which scientists detected in 2022. JADES-GS-z14-0 is thought to be about 40 million years older, based on a detailed analysis of spectroscopic data. Because the age of the universe is estimated at 13.8 billion years, the light from the galaxy took more than 13.5 billion years to reach JWST’s detectors.
Scientists also detected another galaxy, designated JADES-GS-z14-1, that was nearly as distant. And there are likely to be even more distant galaxies still waiting to be discovered.
“This discovery is completely unanticipated and is likely to be seen as the most significant extragalactic discovery with JWST to date,” Brant Robertson, an astronomer at the University of California at Santa Cruz, said today in a news release. Robertson is the lead author on one of three research papers about the discovery.
The findings came out of more than 70 hours’ worth of JWST observations focusing on the spectral signatures of early galaxies, conducted for a campaign called the JWST Advanced Deep Extragalactic Survey, or JADES.
Robertson and his colleagues were surprised to see how bright JADES-GS-z14-0 was — so surprised that they spent months analyzing their readings to confirm that the galaxy was as far away as it seemed to be.
Scientists estimate distances on a cosmic scale by measuring how much the light from a given source has shifted toward the red side of the spectrum due to the expansion of the universe. JADES-GS-z14-0 registered a redshift value of z=14.32, which corresponds to the 13.5 billion-year age estimate.
The research team estimates the size of the galaxy at more than 1,600 light-years in diameter. The brightness and size of the galaxy, plus other clues gathered from JWST’s readings, pose a theoretical puzzle.
“JADES-GS-z14-0 is not like the types of galaxies that have been predicted by theoretical models and computer simulations to exist in the very early universe,” study co-authors Stefano Carniani and Kevin Hainline write in a commentary. “Given the observed brightness of the source, we can forecast how it might grow over cosmic time, and so far we have not found any suitable analogs from the hundreds of other galaxies we’ve observed at high redshift in our survey.”
Fortunately, the JWST team is just getting started.
“We could have detected this galaxy even if it were 10 times fainter, which means that we could see other examples yet earlier in the universe — probably into the first 200 million years,” Robertson said. “This galaxy is truly a gem, and it points at more hidden treasures in the early universe.”
Robertson, Carniani and Hainline are among 36 authors of “Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic Star-Formation Rate Density 300 Myr after the Big Bang,” a study that has been accepted for publication in the Astrophysical Journal. Two other papers are available as pre-prints that have been submitted for peer review: “A Shining Cosmic Dawn: Spectroscopic Confirmation of Two Luminous Galaxies at z~14” and “JWST/MIRI Photometric Detection at 7.7 μm of the Stellar Continuum and Nebular Emission in a Galaxy at z>14.”
