Published: Thu, April 05, 2018
Research | By Clarence Powell

Astronomers discover a clump of black holes around our galaxy's center

Astronomers discover a clump of black holes around our galaxy's center

The Milky Way may be teeming with tens of thousands of black holes lurking at its centre, according to a new study published on Wednesday.

Scientists have suggested for decades that lots of stellar black holes are circling in the center of galaxies, including ours. But if you took the equivalent space around Earth there would be zero black holes, not thousands, Hailey said. But they hadn't seen evidence of them in the Milky Way core until now.

"In a sense, this is the only laboratory we have to study this phenomenon".

"There hasn't been much credible evidence".

Known as Sagittarius A (Sgr A), the supermassive black hole at the heart of our galaxy is surrounded by a halo of gas and dust - believed to be the ideal breeding ground for huge stars that collapse into black holes when they die. Furthermore, black holes from outside the halo are believed to fall under the influence of a supermassive black hole as their energy diminishes, prompting them to be pulled near the celestial giant and held by its force.

This week, a team of scientists led by Charles Hailey, from the University of Columbia (USA), announced in Nature magazine the discovery of several binary systems in which a part of the couple is a black hole. Throughout the MIlky Way, scientists have only been able to find five dozen black holes.

Journal Reference: A density cusp of quiescent X-ray binaries in the central parsec of the Galaxy. "The galactic center is a odd place".

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"These early galaxies seem to have gone through many more "bursts" when they formed stars, instead of forming them at a relatively steady rate like our own galaxy", Sobral said in a statement. So looking for isolated black holes is not a smart way to find them either. "The star dumps gas into a disk around the black hole, and that disk is good at making X-rays".

Black holes, which are vast amounts of matter asked into small areas, are typically ten times larger than our own sun but packed into an area roughly the diameter of NY city.

The team turned to archival data from the Chandra X-ray Observatory to test their approach.

The team observed the X-ray signatures of 12 black hole binaries within three light years of Sagittarius A.

"The Milky Way is pretty big already", study lead author Cristina Martínez-Lombilla, a doctoral candidate at the Astrophysics Institute of the Canary Islands, which is based on the island of Tenerife, said in a statement. "It is going to significantly advance gravitational wave research because knowing the number of black holes in the center of a typical galaxy can help in better predicting how many gravitational wave events may be associated with them".

The researchers analyzed the outer reaches of a number of spiral galaxies, using optical-light data gathered by the ground-based Sloan Digital Sky Survey and near-ultraviolet and near-infrared information collected by NASA's Galaxy Evolution Explorer (GALEX) and Spitzer space telescopes, respectively.

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