There are many things we don't know about black holes because they emit nothing.
Black holes are millions to billions of times the mass of the Sun. Since black holes form from the cores of massive dead individual stars, how do giant monsters grow?
One of the smallest black holes ever seen has been found in a dwarf galaxy. The mass of the Sun is 200,000 times that of the monster at the heart of Mrk .
The findings were presented at a virtual meeting.
"This black hole is among the smallest of the monster black holes," said astronomer Jack Parker of the college. Black holes like this are hard to find.
The discovery suggests that some of the black holes are less than 100 times the mass of the Sun, and that they grow from stellar-mass seeds.
The discovery of black holes in the early Universe is one of the thorns in the stellar-mass model. It's difficult to reconcile the growth of a tiny seed of a stellar core to a giant black hole in a short period of time.
In the early Universe, huge, dense clouds of gas and dust collapsed down into larger black holes that were tens of thousands of times the mass of the Sun, creating a larger starting point from which supermassive black holes can grow.
The direct collapse model is a rare process and this gives us a method to tease out the likelihoods of each scenario. The stellar seed model has more black holes than dwarf galaxies.
There is a catch. It's difficult to see core black holes in dwarf galaxies. Astronomers can use the stars in the center to infer the central black hole in larger galaxies, but dwarf galaxies are too small and dim for this.
The other method is to look for X-rays. This suggests a black hole that is heating material to such insane temperatures that it blasts out high-energy light.
The Chandra X-ray observatory was used by the researchers to study eight dwarf galaxies that may have an active black hole. The X-ray signature of a black hole with a mass around 200,000 times that of the Sun was shown by Mrk 476.
There was something odd about it. The black hole was obscured by a thick cloud of dust, according to the ratio of high-energy X-rays to low-energy X-rays.
The stellar seed scenario could be tipped by this.
"Because buried black holes are even harder to detect than exposed ones, finding this example might mean there are a lot more dwarf galaxies out there with similar black holes," said astronomer Ryan Hickox.
Recent studies suggest that this is the case. Astronomers have been finding black holes in dwarf galaxies in the last few years. The idea that black holes might be able to grow quickly from stellar-mass seeds is supported by these.
We can expect to find more black hole baby chonks as our technology improves.
"We can't make strong conclusions from one example, but this result should encourage much more extensive searches for buried black holes in dwarf galaxies," he said. We're excited about what we learn.
The research was presented at a meeting.
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