There are black holes at the center of the Universe that are so powerful that they can surpass all of the stars in their disks. The ongoing study of these objects has provided a testbed for General Relativity and revealed a great deal.
Astronomers have observed that the massive black holes have huge appetites. A new survey by the NASA Chandra X-ray Observatory shows that some black holes can consume thousands of stars. The results show that some SMBHs needed to consume a lot of stellar matter in order to grow and reach the sizes that they see today.
The research team responsible for this discovery was led by a professor at Washington State University. She was joined by an international team of astrophysicists from The Hebrew University of Jerusalem, the University of Michigan, and the Columbia University. A paper describing their findings was published.
Black hole studies used to be in one of two classes. Smaller black holes, which weigh 5 to 30 solar mass, and supermassive black holes, which weigh millions or even billions of solar mass, are included. Astronomers have found evidence that there is an in-between class of black holes.
There have been many instances where black holes have been observed consuming stars, but there wasn't much evidence that it happened on the scale observed by the Baldassare and her colleagues. The Chandra data of dense star clusters in the centers of the 108 galaxies could be used to explain the runaway growth of a much smaller black hole.
Baldassare said in a Chandra press release that stars in dense clusters provide a breeding ground for intermediate-mass black holes.
Scientists have proposed various theories on how the SMBHs formed. They formed from the collapse of a huge cloud of gas and dust near the center of a galaxy or from the collapse of stars in a back hole that consumed stars and other matter over time.
The first few hundred million years after the Big Bang are believed to be the time when these theories were created. Baldassare and her team theorize that the density of star clusters is the key to the creation of black holes. The density is dependent on how fast the stars are moving.
If the density is above a certain threshold, a stellar-mass black hole at the center of a cluster will rapidly grow as it consumes the stars nearby. The Chandra data showed that the star clusters at the center of NGC 1385, 1566, 3344, and 6503 were more likely to have a black hole than the other ones. The Hebrew University of Jerusalem's Nicholas C. Stone summarized the article.
“This is one of the most spectacular examples we’ve seen of the insatiable nature of black holes, because thousands or tens of thousands of stars can be consumed during their growth. The runaway growth only begins slowing down once the supply of stars starts to run dry.”
The process suggested by the team can happen at any time in the history of the Universe, which suggests that the formation of IMBHs can happen right up until the present day. The results might explain some types of signals detected by theLIGO. Most models of stellar collapse do not predict black holes that are 50 to 100 times the size of the Sun.
Further studies of the centers of active galaxies are needed before any conclusions can be drawn. The team looks forward to more observations that will test their theory.
Chandra is further reading.
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