06 September 2001

Cosmology: Galactic Centre flares up

Cover photo: Chandra telescope image: NASA/CXC; SgrA*: NASA/MIT/PSU/F. Bagnoff, G. Garmire et al..

Like most galaxies, ours appears to contain a central supermassive black hole, a dark object with a mass 2.6 million times that of the Sun coinciding with the position of the radio source Sagittarius A^*. The false-colour image of the central 65 light-years of the Milky Way galaxy on the cover shows Sgr A^* as the bright, point-like source. There has been little direct evidence of accretion onto Sgr A^*, but the observation of X-rays from SgrA^* changes all that. In October 2000 SgrA^* increased 50-fold in X-ray brightness in just a few hundred seconds, suggesting that the emitting region is just outside the event horizon of a supermassive black hole.

Rapid X-ray flaring from the direction of the supermassive black hole at the Galactic Centre
F. K. BAGANOFF, M. W. BAUTZ, W. N. BRANDT, G. CHARTAS, E. D. FEIGELSON, G. P. GARMIRE, Y. MAEDA, M. MORRIS, G. R. RICKER, L. K. TOWNSLEY & F. WALTER
Nature 413, 45-48 (6 September 2001)
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X-rays from the edge of infinity
FULVIO MELIA
The supermassive black hole at the centre of our Galaxy has a strong influence on its surroundings. Astronomers cannot yet see this beast directly but they now have a much better idea of its size.
Nature 413, 25-26 (6 September 2001)
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06 September 2001 table of contents