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

F. K. Baganoff(1), M. W. Bautz(1), W. N. Brandt(2), G. Chartas(2), E. D. Feigelson(2), G. P. Garmire(2), Y. Maeda(2,3), M. Morris(4), G. R. Ricker(1), L. K. Townsley(2), and F. Walter(5)

(1) Center for Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139-4307, USA
(2) Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802-6305, USA
(3) Institute of Space and Astronautical Science, 3-1-1 Yoshinodai, Sagamihara, 229-8501, Japan
(4) Department of Physics and Astronomy, University of California at Los Angeles, Los Angeles, CA 90095-1562, USA
(5) Department of Astronomy, California Institute of Technology, Pasadena, CA 91125, USA

Paper: Nature, 413, 45 (2001)

EPrint Server: astro-ph/0109367


Most galactic nuclei are now believed to harbour supermassive black holes. Studies of stellar motions 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 million solar masses. This object is spatially coincident with Sagittarius A* (Sgr A*), the unique compact radio source located at the dynamical centre of our Galaxy. By analogy with distant quasars and nearby active galactic nuclei (AGN), Sgr A* is thought to be powered by the gravitational potential energy released by matter as it accretes onto a supermassive black hole. However, Sgr A* is much fainter than expected in all wavebands, especially in X-rays, casting some doubt on this model. Recently, we reported the first strong evidence of X-ray emission from Sgr A*. Here we report the discovery of rapid X-ray flaring from the direction of Sgr A*. These data provide compelling evidence that the X-ray emission is coming from accretion onto a supermassive black hole at the Galactic Centre, and the nature of the variations provides strong constraints on the astrophysical processes near the event horizon of the black hole.

Preprints available from the authors at fkb@space.mit.edu , or the raw TeX (no figures) if you click here.

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