Artist’s impression of a quasar used by astronomers to search for early galaxies
ESO/M.Kornmesser
One of the largest quasars in the early Universe has helped reveal a vast “primordial cluster” of early galaxies, which is expected to grow larger than any galaxy cluster we know of.
Protoclusters are the primordial beginnings of the galaxy clusters we see in this region of the universe, before they were bound together by gravity. Astronomers typically search for them by pointing telescopes across large swaths of space, trying to find regions with unusually large numbers of early galaxies.
Instead, Feige Wan He and his colleagues at the University of Arizona decided to focus on quasars, the luminous centers of galaxies that emit light when gas falls into supermassive black holes. They chose one of the heaviest and brightest quasars known from the early Universe. That light is only now reaching us, 800 million years after the Big Bang, and we hope it will serve as a guide to other giant objects around us.
They discovered a vast web of early galaxies surrounding the quasar. “This protocluster is huge,” Wang said. “If you look at it in the sky compared to other protoclusters, you’ll see that it’s only a few arc minutes across the sky, but this protocluster is several tens of minutes across the sky.” It’s degree.
Primordial galaxy clusters are expected to grow over time and eventually collapse into galaxy clusters. If this happens, Wang and his team calculate that their combined mass would be about 70 quintillion times that of the Sun, potentially larger than the largest known galaxy cluster in this region of the universe.
The quasar at the center of the cluster is a supermassive black hole, probably about 3 billion times more massive than the Sun. According to Dr. Wang, it is difficult to explain how this black hole grew to such a huge size in such a short period of time after the birth of the universe, but if a system similar to this can be discovered, this problem could be solved. The study could help elucidate the effects of such huge quasars. nearby galaxy.
Proto-galactic clusters are extremely dense environments, providing important clues to explain the rapid growth of quasars, they say. david alexander At Durham University, UK. “In such a dense environment, a large amount of gas is available to fuel the black hole, allowing it to grow rapidly,” he says.
But he says we will need to find many more objects like it before we can begin to explain how early supermassive black holes got so big.
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