Integral Hard X-ray image of the center of the Milky Way
Credit: M. G. Revnivtsev et al.; INTEGRAL

Reflections of a More Active Time

You look younger the more distant the mirror. That seems to be the lesson learned by astronomers in new images of hard X-ray emission of the center of the Milky Way. An X-ray image (shown above) obtained by the INTEGRAL observatory shows a number of hard X-ray sources near the center of our Galaxy. One of the weaker sources is Sgr A* (marked by a white cross in the lower image). Sgr A* thought to be location of the Milky Way's supermassive black hole. This black hole is a surprisingly weak X-ray source, which means that the black hole is not consuming much matter. But evidently it was not always such. The source identified as Sgr B2 in the lower image shows that this object is also a weak X-ray source, also a bit of a surprise since Sgr B2 is a giant molecular cloud, too cold to produce hard X-ray emission on its own. Sgr B2 is about 350 lightyears from Sgr A*, so astronomers think that the observed X-rays from Sgr B2 are the reflection of X-rays from Sgr A* from about 350 years earlier, when the black hole was apparently much more active and brighter in X-rays.

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Page Author: Dr. Michael F. Corcoran
Last modified Friday, 20-Apr-2012 15:25:30 EDT