NASA’s Space Telescope Uncovers Earliest Galaxies Challenging Formation Theories

An international team of astronomers announced the two earliest and most distant galaxies yet confirmed were detected by the James Webb Space Telescope. The two galaxies are believed to date back to just 300 million years after the Big Bang.

Over the past two years, scientists have utilized NASA’s Webb telescope to explore what astronomers refer to as the Cosmic Dawn, which is the period of time in the first few hundred million years following the Big Bang. Astronomers and scientists used the newfound data to gain vital insight into how gas, stars, and black holes were changing during the early years of the Universe.

In October 2023 and January 2024, an international team of astronomers used Webb to observe galaxies as part of the JWST Advanced Deep Extragalactic Survey (JADES) program. By using Webb’s NIRSpec instrument, the team was able to detect a spectrum of a record-breaking galaxy observed only two hundred and ninety million years after the Big Bang.

“These galaxies join a small but growing population of galaxies from the first half billion years of cosmic history where we can really probe the stellar populations and the distinctive patterns of chemical elements within them,” explained Dr Francesco D’Eugenio of the Kavli Institute for Cosmology at the University of Cambridge.

Along with the two noted galaxies, the team added they found many hundreds of candidate galaxies from the first 650 million years after the Big Bang. During early 2023, the team discovered a galaxy in its data that had strong evidence of being above a redshift of 14. However, some properties still had the team a bit wary of the findings.

“The source was surprisingly bright, which we wouldn’t expect for such a distant galaxy, and it was very close to another galaxy such that the two appeared to be part of one larger object,” remarked Stefano Carniani from Scuola Normale Superiore in Pisa, Italy. “When we observed the source again in October 2023 as part of the JADES Origins Field, new imaging data obtained with Webb’s narrower NIRCam (Near-Infrared Camera) filters pointed even more toward the high-redshift hypothesis. We knew we needed a spectrum, as whatever we would learn would be of immense scientific importance, either as a new milestone in Webb’s investigation of the early universe or as a confounding oddball of a middle-aged galaxy.”

The observations also brought some questions. One of those questions is that JADE-GS-z14-0 is not like the types of galaxies that have been predicted by theoretical models and computer simulations to exist in the early universe. The team noted that given the “relatively small region of the sky” they searched to find the distant galaxy, its discovery has “profound implications for the predicted number of bright galaxies" observed in the early universe.

In keeping with the collaboration’s standard naming practice, the galaxies are now known as JADES-GS-z14-0 and JADES-GS-z14-1, with the former being the most distant of the two. Adding to the excitement of the finds, JWST measures JADES-GS-z14-0 at over 1,600 light-years in diameter.

Astronomers and scientists hope that they will be able to see even further into the Universe’s past, perhaps into the first 200 million years, using Webb. Brant Robertson, professor of astronomy and astrophysics at the University of California-Santa Cruz, remarked, “The early Universe has so much more to offer.”