Less than a week after the James Webb Space Telescope was ready for science, the first reports of discoveries of galaxies at record distances and, therefore, at record early times, appeared in preprint editions. More importantly, these galaxies appear so massive that they defy our understanding of how structure in the universe forms.
Now the first two of these reports have undergone mandatory peer review and have been accepted for publication in the Scientific journal Astrophysical Journal Letters, which proves the robustness of the result. However, astronomers are still waiting for the definitive proof – spectroscopy.
Just five days after the James Webb Space Telescope began its science observations in July, the first reports of record-breaking came in galaxies Back. not yet Scientific journalsbut on the arXiv.org preprint server where researchers, eager to publish their findings, usually upload their manuscripts simultaneously with submissions to journals.
Although the articles have not yet gone through the peer-review process that is so critical to science, they have naturally attracted media attention.
Notes that challenge theories
It wasn’t just that the explored universe had now grown in size. What’s even more interesting is that the galaxies apparently host more stars than we ever thought possible. Indeed, the very basics of our understanding of how massive structures accumulate over time are being challenged; “The Cosmological Standard Model”.
“From a theoretical point of view, the observed masses are very puzzling,” explains Charlotte Mason, associate professor at the Center for Cosmic Dawn (DAWN) in Copenhagen. “We expect that we will have to search a much larger area of space before finding such large galaxies. The average galaxy simply has not had time to build up a very large mass in the short period between the Big Bang and the time we see them.”
Mason is the co-author of one of the first two papers now accepted for publication. This work, led by Marco Castellano at the INAF Osservatorio Astronomico di Roma, reports on the discovery of many more distant galaxies on record.
The report appeared in preprint simultaneously with another paper, led by MIT’s Rohan Naidu, which analyzed the same field in the sky and found many of the same galaxies.
Fairly strong result
As detailed in a recent press release from the Cosmic Dawn Center, the technique used to determine distances is a quick but somewhat unreliable method, which has been known to occasionally confuse nearby galaxies (or even local stars) with very distant galaxies. To confirm the distance, each galaxy must be followed up with a more time-consuming spectrometer, in which the exact wavelength of each photon is measured.
Despite the missing spectral analysis, the distances between two galaxies – dubbed GLASS-z10 and GLASS-z12 – appear fairly clear. And the fact that two different teams, using two different analyzes of the same data, found the same distance is reassuring.
Moreover, the analysis by Naidu’s team was used in exactly the same way for a slightly less distant galaxy, as also observed with James Webb, and recently confirmed through spectroscopy by a third team led by Haley Williams at the Minnesota Astrophysical Institute.
Gabriel Brammer, associate professor at DAWN, was involved in studies conducted by both Naidu’s team and Williams’ team. He is also the developer of software used for data analysis. As is common in astronomy, Brammer’s software is publicly available, and is a popular tool among other astronomers.
“We used the same software and analysis for another galaxy as distant, roughly the same as GLASS-z10. I was very happy to see our results confirmed by spectroscopy. This demonstrates the capability of the analysis and gives us confidence that the extrapolated result is rather robust,” says Brummer.
Early evolution of the galaxy
Although the large masses of galaxies are difficult to reconcile with our current understanding of structure formation, this does not necessarily mean that we will need to revise the Standard Model of the Universe. Several less dramatic, but also interesting explanations are in the works:
“We know very little about it physical condition “The early universe,” says Pascal Ochs, second author on Naidoo’s paper and associate professor at DAWN. Throughout most of the history of the universe, galaxies have been surprisingly inefficient at forming stars. A hitherto unknown mechanism may have enabled early galaxies to form stars faster, or to form brighter stars. “
With upcoming spectroscopy, as well as near-future observations scanning larger volumes of space, the true nature of these and similar mysterious galaxies will soon be revealed.
Naidu et al. Rohan B. arXiv (2022). DOI: 10.48550/arxiv.2207.09434
Marco Castellano et al., Early results from GLASS-JWST. Third. Galaxy candidates at z ∼9–15*, Astrophysical Journal Letters (2022). DOI: 10.3847/2041-8213/ac94d0
Hayley Williams et al, Spectroscopy from Lyman alpha to [O III] 5007 for a magnified galaxy imaged three times at Redshift z = 9.5, arXiv (2022). DOI: 10.48550/arxiv.2210.15699
Niels Bohr Institute
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