Rapid X-ray flaring from the direction of the supermassive black hole at the Galactic Centre


The nuclei of most galaxies are now believed to harbour supermassive black holes1. The motions of stars in the central few light years of our Milky Way Galaxy indicate the presence of a dark object with a mass of about 2.6 × 106 solar masses (refs 2, 3). This object is spatially coincident with the compact radio source Sagittarius A* (Sgr A*) at the dynamical centre of the Galaxy, and the radio emission is thought to be powered by the gravitational potential energy released by matter as it accretes onto a supermassive black hole4,5. Sgr A* is, however, much fainter than expected at all wavelengths, especially in X-rays, which has cast some doubt on this model. The first strong evidence for X-ray emission was found only recently6. Here we report the discovery of rapid X-ray flaring from the direction of Sgr A*, which, together with the previously reported steady X-ray emission, provides compelling evidence that the emission is coming from the accretion of gas onto a supermassive black hole at the Galactic Centre.

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Figure 1: Surface plots of the 2–8 keV counts within a 20″ × 20″ field centred on Sgr A* at two epochs.
Figure 2: Light curves of the photon arrival times and band ratios from the direction of Sgr A* on 26–27 October 2000.
Figure 3: X-ray spectra of the Chandra source at the position of Sgr A*.


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We thank M. Begelman for useful comments. This work has been supported by a grant from NASA.

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Correspondence to F. K. Baganoff.

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Baganoff, F., Bautz, M., Brandt, W. et al. Rapid X-ray flaring from the direction of the supermassive black hole at the Galactic Centre. Nature 413, 45–48 (2001). https://doi.org/10.1038/35092510

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