Thousands Of Black Holes Discovered In The Center Of Milky Way

Using data from NASA’s Chandra X-ray Observatory, researchers have discovered a massive swarm of black holes near the center of our galaxy Milky Way. The newly identified black holes are stellar-mass black holes which are formed by the gravitational collapse of extremely massive stars and typically weigh between five to 30 times the mass of the sun. These black holes are lying three light years away from Sagittarius A*, the supermassive black holes in the center of galaxy. This is a relatively short distance in cosmic terms.

Scientists have long assumed that Milky Way hosts a large population of stellar mass black holes in its center because of the halo of gas and dust around Sagittarius A*. This region of gas and dust could serve as a perfect breeding ground for the birth of massive stars, which live, die and could turn into black holes. Extensive searches have been made for these black holes over the years but no population has been detected until now. The recent analysis of Chandra data is the first observational evidence of such a treasure trove of black holes.

Black holes themselves are invisible objects, so we cannot directly see them. However, a black hole or a neutron star locked in close orbit with another star constantly pulls material away from its stellar companion, which falls onto a disk and produces momentary X-rays. The bright burst of X-ray glow that occurs in black hole binaries are sometimes captured by observatories like Chandra. When researchers used Chandra data to search for X-ray binaries containing black holes that are located near Sgr A*, they detected fourteen X-ray binaries within about three light years of the supermassive black hole. Based on the characteristic outbursts, researchers concluded that majority of these dozen X-ray binaries are likely to contain black holes instead of neutron stars. There must be anywhere from 300 to a thousand stellar-mass black holes in the area surrounding Sgr A*. The detection of such a large population of confirms a decades-old prediction and provides opportunity to better understand the universe.

“The existence of a ‘density cusp’ – a localized increase in number – of stellar-mass black holes near a supermassive black hole is a fundamental prediction of galactic stellar dynamic. The best place to detect such a cusp is in the Galactic Centre, where the nearest supermassive black hole, Sagittarius A*, resides,” Authors wrote in the study.

“The properties of these X-ray binaries, in particular their spatial distribution and luminosity function, suggest the existence of hundreds of binary systems in the central parsec of the Galaxy and many more isolated black holes.”

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