New JWST observations uncover mysterious ancient galaxy

Our understanding of galaxy formation and the nature of dark matter could be completely upended after new observations of a stellar population larger than the Milky Way, more than 11 billion years old, that is unlikely to exist .

An article published today in Nature details results obtained using new data from the James Webb Space Telescope (JWST). The results reveal that a massive galaxy in the early universe – observed 11.5 billion years ago (a cosmic redshift of 3.2) – has an extremely ancient population of stars formed much earlier – 1.5 billion years earlier (a redshift of about 11). The observation upsets current modeling, because there is not enough dark matter accumulated at sufficient concentrations to initiate their formation.

Distinguished Professor Karl Glazebrook from Swinburne University of Technology led the study and the international team, which used the JWST for spectroscopic observations of this immense galaxy at rest.

“We have been tracking this particular galaxy for seven years and spent hours observing it with the world’s two largest telescopes to determine its age. But it was too red and too faint, and we couldn’t measure it at the time. In the end, we had to leave Earth and use the JWST to confirm its nature.”

Galaxy formation is a fundamental paradigm underlying modern astrophysics and predicts a sharp decline in the number of massive galaxies at the beginning of cosmic time. Extremely massive quiescent galaxies were observed one to two billion years after the Big Bang, challenging previous theoretical models.

Distinguished Professor Glazebrook has worked with leading researchers around the world including Dr Themiya Nanayakkara, Dr Lalitwadee Kawinwanichakij, Dr Colin Jacobs, Dr Harry Chittenden, Associate Professor Glenn G Kacprzak and Associate Professor Ivo Labbe of the Swinburne Center for Astrophysics and Supercomputing. .

“It was largely a team effort, from the infrared sky studies we began in 2010 that led us to identify this galaxy as unusual, to our many hours spent on the Keck and the Very Large Telescope where we tried, unsuccessfully, to confirm it, until finally the last year where we put enormous effort into figuring out how to process the JWST data and analyze that spectrum.

Dr Themiya Nanayakkara, who led the spectral analysis of the JWST data, says: “We are now going beyond what was possible to confirm the oldest massive, silent monsters that exist deep in the universe. This pushes the limits of our current understanding of how galaxies form and evolve. The key question now is how they form so quickly very early in the universe, and what mysterious mechanisms lead to preventing them from forming. abruptly stars while the rest of the universe does.”

Associate Professor Claudia Lagos from the University of Western Australia node of the International Center for Radio Astronomy Research (ICRAR) played a crucial role in developing theoretical modeling of the evolution of dark matter concentrations for the study.

“The formation of galaxies is largely dictated by how dark matter concentrates,” she says. “The presence of these extremely massive galaxies so early in the universe poses significant challenges to our standard model of cosmology. Indeed, we do not believe that dark matter structures as massive as they host these massive galaxies have yet had time to form. are necessary to understand how common these galaxies may be and to help us understand how massive these galaxies really are.

Glazebrook hopes this could be a new opening for our understanding of dark matter physics, saying: “JWST has discovered increasing evidence for the early formation of massive galaxies. This result sets a new record for this phenomenon. Although it is very striking, it is only one object. But we hope to find more, and if we do, it will really shake up our ideas about galaxy formation.