mercredi 30 mai 2018

Black Hole Bounty Captured in the Center of the Milky Way

NASA - Chandra X-ray Observatory patch.

May 30, 2018

Astronomers have discovered evidence for thousands of black holes located near the center of our Milky Way galaxy using data from NASA's Chandra X-ray Observatory.

This black hole bounty consists of stellar-mass black holes, which typically weigh between five to 30 times the mass of our Sun. These newly identified black holes were found within three light years — a relatively short distance on cosmic scales — of the supermassive black hole at our Galaxy's center known as Sagittarius A* (Sgr A*).

Theoretical studies of the dynamics of stars in galaxies have indicated that a large population of stellar mass black holes — as many as 20,000 — could drift inward over the eons and collect around Sgr A*. This recent analysis using Chandra data is the first observational evidence for such a black hole bounty.

A black hole by itself is invisible. However, a black hole — or neutron star — locked in close orbit with a star will pull gas from its companion (astronomers call these systems "X-ray binaries"). This material falls into a disk and heats up to millions of degrees and produces X-rays before disappearing into the black hole. Some of these X-ray binaries appear as point-like sources in the Chandra image.

Chandra X-Ray Observatory:

Image, Text, Credits: NASA/Yvette Smith/Chandra X-Ray Observatory.


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