Sagittarius A*, the unusually dim supermassive black hole at the heart of the Milky Way (pictured), may have flared up at times during the past few centuries.
Observations from NASA's Chandra X-ray Observatory between 1999 and 2011 reveal bright patches of X-rays in molecular clouds in the centre of the Galaxy. The glow, which has been rippling outwards, could be reflected radiation that was emitted from the black hole long ago, and then bounced off nearby clouds.
Maica Clavel of the Paris Diderot University and her colleagues calculate that two sudden surges in the black hole's activity — one lasting no more than two years, and the other about a decade — could produce the observed reflections. Charting them may help to reveal what the black hole has been consuming.
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Reflections from a black hole. Nature 502, 275 (2013). https://doi.org/10.1038/502275a
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DOI: https://doi.org/10.1038/502275a
