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Black hole boldly goes where no black hole has gone before   Black holes are, by definition, invisible. But the region around them can flare up periodically when the black hole feeds. As gas falls into a black hole, it will heat to high temperatures and radiate brightly, particularly in X-rays.
Thanks to ESA’s XMM-Newton data, astronomers found one stellar-mass black hole by chance feeding in a globular star cluster in a galaxy named NGC 4472 (or M49), about fifty million light-years away in the Virgo Cluster.  Globular clusters are dense bundles of thousands to millions of old stars, and many scientists have doubted that black holes could survive in such an exclusive environment. Computer simulations show that a newly formed black hole would first sink towards the centre of the cluster but quickly get gravitationally slingshot out entirely when interacting with the cluster's myriad stars.
New XMM-Newton findings provided the first convincing evidence that some black hole might not only survive but grow and flourish in globular clusters.  Astronomers using XMM-Newton data found that the elliptical galaxy (named NGC 4472 or M49) shown in this image hosts a stellar-mass black hole in the act of feeding. This black hole is the first ever found in a globular star cluster.
The galaxy is situated about fifty million light-years away in the constellation Virgo, one of the many members of the Virgo galaxy cluster. This image was taken in December 1996 at the KPNO 0.9-metre telescope. Release date: 3 January 2007 |