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Saturday, June 8, 2013

a throng of small black holes lurks incognito near Sagittarius A

An immense cloud of gas currently swooping around the centre of our galaxy could reveal a multitude of small black holes nestled close to its heart. Over the next 12 months, the G2 gas cloud will pass through the galactic centre where, according to the calculations of astrophysicists in the US, encounters with small black holes will produce bursts of radiation that could be detectable using space telescopes.
Since the 1970s astronomers have postulated that a throng of small black holes lurks incognito near Sagittarius A*, the supermassive black hole at the centre of the Milky Way. Through a process known as dynamical friction, the most massive objects in the galaxy slow down as they move through the interstellar medium, and so drift gradually towards the centre. Based on star formation and death rates, simulations predict a population of around 20,000 small-scale black holes in the innermost region of the galaxy, each with a mass several times that of our Sun. So goes the theory, anyway, but until now there has been no way of actually testing it.