An article published in “The Astrophysical Journal” reports the results of a study of primordial galaxies that seemed too massive for their age, concluding that it was actually the light generated by the activity of their supermassive black holes that created a wrong impression. A team of researchers led by Katherine Chworowsky, a graduate student at the University of Texas at Austin (UT Austin), examined observations conducted with the James Webb Space Telescope as part of the Cosmic Evolution Early Release Science (CEERS) survey to reach these conclusions.
If this interpretation of the brightness of these primordial galaxies is confirmed, it will eliminate the difficulties in explaining their quick evolution according to current cosmological models. Some primordial galaxies remain more massive than expected, but they can be explained by a significant star formation.
The James Webb Space Telescope is providing the astronomical observations hoped for, revealing among other things new primordial galaxies and providing many new details of primordial galaxies already known. The problem arose when the brightness of some of those galaxies seemed abnormal for their age. This had led to estimates that they were much more massive than current cosmological models predict for galaxies that formed so early.
The new analysis reported in this study offers an explanation for the galaxies that seemed the most massive and were hard to explain within current models. According to the researchers, some of the light coming from those galaxies is actually produced not by stars but by materials that surround the supermassive black holes at their centers and are heated to the point of generating electromagnetic emissions.
Analyzes of the chemical signatures left by various chemical elements in the spectral emissions captured by the James Webb telescope allowed to find evidence of the activity of the supermassive black holes at the centers of the galaxies examined. That activity was detected in the form of quickly moving hydrogen, a sort of signature typical of the accretion disks that surround those black holes, where they are heated.
Professor Steven Finkelstein of UT Austin, who led the CEERS survey and is one of the authors of this new study, noted that when there’s a theory that has stood the test for a long time, it takes overwhelming evidence to throw it out and this is not the case.
It should be noted that there remain more massive galaxies than expected that don’t require a rethinking of cosmological models but still need to be explained. One possibility is that star formation was greater than today. There are astronomers who believe that the higher density of the early universe favored star formation processes. This is a theory that could now be tested thanks to the James Webb Space Telescope.
All this means that there’s an explanation for the galaxies that appeared the most massive but more studies are needed to understand the processes at work in other massive early galaxies. The James Webb Space Telescope is offering performances that are sometimes even better than expected and this could help astronomers better understand the early stages of the history of the universe.
