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Our understanding of how galaxies form and the nature of dark matter could be completely altered, after new observations of a stellar population larger than the Milky Way from more than 11 billion years ago that should not exist.
An article published in Nature details the findings using new data from the James Webb Space Telescope (JWST). The results find that a massive galaxy in the early universe, observed 11.5 billion years ago (a cosmic redshift of 3.2), has an extremely old population of stars formed much earlier: 1.5 billion years ago (a cosmic redshift of 3.2). red about 11). The observation disrupts current models, since not enough dark matter has accumulated in sufficient concentrations to seed its formation.
Distinguished Professor Karl Glazebrook of Swinburne University of Technology led the study and the international team that used JWST for spectroscopic observations of this huge, inactive galaxy.
“We have been chasing this particular galaxy for seven years and spent hours observing it with the two largest telescopes on Earth to determine its age. But it was too red and too faint and we couldn’t measure it. In the end, we had to leave Earth and use JWST to confirm its nature.”
NASA’s James Webb Space Telescope is the successor to the Hubble Space Telescope, the most powerful infrared scientific observatory ever sent into space. From its orbit nearly a million kilometers from Earth, Webb studies some of the most distant objects in the universe. Credit: NASA
Galaxy formation is a fundamental paradigm underpinning modern astrophysics and predicts a sharp decline in the number of massive galaxies in early cosmic times. Extremely massive dormant galaxies have been observed as early as one to two billion years after the big Bang which challenges previous theoretical models.
Distinguished Professor Glazebrook worked with leading researchers from 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 from the Swinburne Center for Astrophysics and Supercomputing. .
“This was very much a team effort, from the infrared sky surveys we began in 2010 that led us to identify this galaxy as unusual, to the many hours we spent at Keck and Very large telescope where we tried, but couldn’t confirm it, until finally last year, where we put a huge amount of effort into figuring out how to process the JWST data and analyze this spectrum.”
Dr Themiya Nanayakkara, who led the spectral analysis of the JWST data, says: “We are now going beyond what is possible to confirm the oldest massive dormant 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 and so early in the Universe and what mysterious mechanisms prevent them from abruptly forming stars when the rest of the Universe does.”
Associate Professor Claudia Lagos of the International Radio Astronomy Research Center node at the University of Western Australia (ICRAR) was crucial in developing theoretical modeling of the evolution of dark matter concentrations for the study.
“Galaxy formation depends largely on how dark matter is concentrated,” he says. “Having these extremely massive galaxies at such an early stage in the Universe poses significant challenges to our standard model of cosmology. This is because we do not believe that dark matter structures as massive as those that house these massive galaxies have not yet had time to form. “More observations are needed to understand how common these galaxies may be and help us understand how truly massive these galaxies are.”
Distinguished Professor Glazebrook hopes that this could be a new opportunity for our understanding of the physics of dark matter.
“JWST has been finding increasing evidence of massive galaxies forming early in time. This result sets a new record for this phenomenon. Although it is very striking, it is only an object. “But we hope to find more, and if we do, this will really alter our ideas about galaxy formation.”
Reference: “A massive galaxy that formed its stars at z ~ 11” by Karl Glazebrook, Themiya Nanayakkara, Corentin Schreiber, Claudia Lagos, Lalitwadee Kawinwanichakij, Colin Jacobs, Harry Chittenden, Gabriel Brammer, Glenn G. Kacprzak, Ivo Labbe, Danilo Marchesini , Z. Cemile Marsan, Pascal A. Oesch, Casey Papovich, Rhea-Silvia Remus, Kim-Vy H. Tran, James Esdaile and Angel Chandro-Gomez, February 14, 2024, Nature.
DOI: 10.1038/s41586-024-07191-9