NASA / CXC/ M. Weis
The Milky Way glutton: black hole Sagittarius A* emits X-rays as it feeds on material from G2 objectNASA / CXC/ M. WeisThe black hole at the center of the Milky Way has been more active lately. Since mid-2014, astronomers in Europe and the United States have reported an increase in the frequency of X-ray emissions near Sagittarius A*, our galaxy’s black hole. Since regular monitoring of this region of space began about 15 years ago, Sagittarius A* had seemed relatively mild-mannered. X-ray bursts are typically detected in its vicinity once every 10 days. Flashes of high-energy light, invisible to the human eye, are emitted every time heated gas from the accretion disk falls towards the black hole. A little over a year ago, however, the frequency of these flashes increased tenfold, to once a day, a sign that Sagittarius A* had suddenly become more voracious (MNRAS, in press). Astronomers still don’t know whether this fluctuation is part of a natural cycle or the result of an object passing through the neighborhood. The flashes became more frequent six months after an object named G2, possibly a gas-enveloped star, approached the black hole.
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