It lurks in the heart of our home galaxy the Milky Way: a huge black hole named Sagittarius A*, surrounded by clouds of rock and debris. About once a day, intense bursts of X-ray radiation flare up from the vicinity of the black hole and burn for a few hours before dying out.

Researchers in our Department of Physics and Astronomy believe they have found the reason why. Dr Sergei Nayakshin and research student Kastytis Zubovas believe the flares are caused by Sagittarius A* pulling asteroids into its massive gravitational field and tearing them apart. The rocks, which can be several miles wide, plunge towards Sagittarius A* at high speeds and are vaporised by friction with the gas clouds that continuously circle the black hole.

Zubovas and Nayakshin suggest that Sagittarius A* is orbited by hundreds of trillions of asteroids and comets, space rocks stripped from their parent stars and planets and drawn in by the black hole's gravitational pull. Periodically, asteroids are thrown off their normal orbits and flung towards the galactic core, where Sagittarius A* pulls them apart and sucks them in.

The researchers studied data from NASA's Chandra X-Ray Observatory, in collaboration with Sera Markoff of the University of Amsterdam in the Netherlands. Their findings are published in the Monthly Notices of the Royal Astronomical Society.

• University Press Release
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