According to a new study, some of the primordial galaxies are actually much less massive than they first appeared.
When astronomers have the first images of the oldest galaxies of the universe from the James Webb Space Telescope, they expected to find small galaxies, but instead they found what appeared to be . Some galaxies appeared to have become so massive, and so quickly, that simulations couldn’t explain them.
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According to a new Astronomical Journal study led by University of Texas student Katherine Chworowsky, some of those early galaxies are actually much less massive than they first appeared. Black holes in some of these galaxies make them appear much brighter and larger than they actually are.
Black holes increase in brightness
According to this study, galaxies that appeared excessively massive likely host black holes that consume gas rapidly. Friction in the fast-moving gas emits heat and light, making these galaxies much brighter than they would be if that light were given off. This “extra” light can make galaxies appear to contain many more stars and therefore be more massive than we would otherwise estimate.
“So, the bottom line is that there is no crisis in terms of the standard model of cosmology,” Finkelstein said. “Anytime you have a theory that has stood the test of time for this long, you have to have overwhelming evidence to really discard it. And this is simply not the case.”
More evidence of black holes
Simultaneously, astronomers analyzed the spectra of the “little red dots” discovered with Webb, with researchers from both the CEERS team and others finding evidence of fast-moving hydrogen gas, a signature of accretion disks. This supports the idea that at least some of the light from these compact, red objects comes from gas swirling around the black holes, rather than from stars, strengthening Chworowsky and his team’s conclusion that they are probably not as massive as astronomers initially thought.
