Long-rumored midsized black hole may be hiding out in the Milky Way
Source: Science Magazine
Long-rumored midsized black hole may be hiding out in the Milky Way
By Daniel ClerySep. 4, 2017 , 11:00 AM
Astronomers have found the best evidence yet for the existence of a midsized black hole—long-rumored objects bigger than the small black holes formed from a single star, yet far smaller than the the giant ones lurking at the centers of galaxies—and it’s hiding out in our own Milky Way. If the discovery is confirmed, it could indicate that our galaxy has grown by cannibalizing its smaller neighbors.
“It’s a very careful paper and they have gorgeous data. It’s the most promising evidence so far” for an intermediate mass black hole, says astronomer Kevin Schawinski of the Swiss Federal Institute of Technology in Zurich.
Black holes are hard to see because they don’t emit their own light. But they can be detected by their influence on nearby objects, for example if the black hole is in a binary pair with a star, or if it is consuming gas which gets heated as it approaches and shines brightly. Astronomers have long found evidence for small, star-sized black holes—up to about 10 times the sun’s mass—and supermassive ones, containing millions or billions of solar masses, in galactic cores.
But intermediate-sized black holes have eluded detection. The best candidates so far have been so-called ultraluminous x-ray sources in nearby galaxies. But researchers are divided over whether these are really midsized black holes, shining bright as they imbibe lots of surrounding gas, or smaller ones ingesting at a superfast rate.
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Read more: http://www.sciencemag.org/news/2017/09/long-rumored-midsized-black-hole-may-be-hiding-out-milky-way
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Related: Millimetre-wave emission from an intermediate-mass black hole candidate in the Milky Way (Nature Astronomy)
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ARTIST'S IMPRESSION OF THE BLACK HOLE TOMOHARU OKA/KEIO UNIVERSITY
By Alfredo Carpineti
04 SEP 2017 16:00
Astronomers from Keio University, Japan, have observed what looks like the largest intermediate-mass black hole within the Milky Way. The object is estimated to weigh 100,000 times the mass of the Sun and is located near the center of the galaxy.
The study, published in Nature Astronomy, focused on a large molecular gas cloud almost 200 light-years from the center of the Milky Way. The team was able to study how the gas is moving, which is consistent with having a massive compact object at its center, which they named CO–0.40–0.22*.
The researchers also noticed how the emissions from the gas cloud resemble the core of the Milky Way, where the supermassive black hole of our galaxy is located, although 500 times less luminous. There’s also quite a difference in size as the Milky Way's supermassive black hole, called Sagittarius A*, is over 4 million times the mass of the Sun.
"This is the first detection of an intermediate-mass black hole (IMBH) candidate in our Milky Way Galaxy," lead author Dr Tomoharu Oka told IFLScience. "This supports the merging scenario of the formation/evolution of supermassive black holes in galactic centers."
More:
http://www.iflscience.com/space/black-hole-100000-times-the-mass-of-the-sun-discovered-in-our-own-galaxy/