Astronomers Are Hunting Stupendously Large Black Holes That Dwarf Supermassive
Most everyone is familiar with the large black hole that exists at the center of the Milky Way, Sagittarius A*. While it may appear to be massive in terms of size, it is actually quite small in comparison to many others throughout the Universe. Some are known to be 1,000 times more massive than Sagittarius A*, and large enough to span the entire width of our solar system. One in particular, Ton 618, is known to be 66 billion times the mass of Earth’s Sun, and is up to 40 times wider than the distance between Neptune and the Sun. While that may sound impossible to beat, some scientists believe there could be even larger ones.
“From a theoretical perspective, there’s no limit,” explained James Nightengale, an observational cosmologist at Newcastle University in the UK.
With the advent of the James Webb telescope, astronomers and scientists have been able to venture further back into the beginning of time. This is allowing them to detect galaxies in what they believe to be the first few hundred million years of the Universe’s existence. It is also providing evidence for something that defies much of what they believed to know about the limits on how black holes form and grow.
JWST has revealed previously unseen types of galaxies which shine brighter than expected, and believed to have existed around 600 million years to one billion years after the Big Bang. What is most surprising about them is the amount of light they emit, which seems to indicate supermassive black holes already inside them.
The fact JWST is finding black holes that are the same size as their own galaxy right so early in the history of Universe, suggests that black holes may have formed first before galaxies grew around them. Hannah Ubler, a cosmologist at the University of Cambridge in the UK, says these are “tens to a few hundred” times larger than expected. She added that astronomers refer to these early black holes as “overmassive black holes,” and it is “really surprising and really puts a challenge to theoretical models to explain how these black holes managed to grow so massive so quickly.”
While there are a few theories as to how these supermassive black holes grew to their sizes, it remains unclear how large black holes might be in the modern cosmos. Julie Hlavacek-Larrondo, an astrophysicist at the University of Montreal, remarked, “We have this rough estimate based on the age of the Universe. But Maybe the Universe will surprise us.”