A galaxy far, far away ­ with a 'monstrous' black hole at its heart

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Astronomers have taken one of the most detailed photographs yet of a massive black hole at the centre of a distant galaxy as it sucks in unimaginable quantities of surrounding matter.

The image, released yesterday, shows the intense light emitted by material just before it is swallowed up by an active black hole in the M81 spiral galaxy in the constellation Ursa Major, 12 million light years from Earth.

Scientists from the Mullard Space Science Laboratory at University College London (UCL) built the ultraviolet telescope on board the XMM-Newton satellite, a space observatory launched in 1999 that shows the galaxy in unprecedented clarity.

Keith Mason, professor of astronomy at UCL, said it was the first time that the M81 galaxy had been seen in such detail despite being photographed by the Hubble space telescope, working in the optical region of the electromagnetic spectrum.

Taking images in the ultraviolet region, and comparing them with the X-rays emitted from the galaxy that are detected by another instrument on board the Newton space observatory, the scientists have built up a picture of the "monstrous" black hole. The gravitational pull of a black hole is so strong that even light cannot escape from it. "You can't actually see a black hole, you can only see its effects," Professor Mason explained.

With a mass approaching 10 million times that of the Sun, the black hole acts as a magnet for nearby objects, ranging from interstellar dust to stars. As the matter is sucked in, it is heated to tens of millions of degrees, causing intense amounts of light and radiation to be released.

When the matter crosses the "event horizon" of the black hole, however, nothing can escape, Professor Mason said.

Elizabeth Puchnarewicz, a member of the UCL team, said it was probable that all galaxies ­ including our own Milky Way ­ had black holes at their cores, although not all of them were active.

"We think another galaxy passed through M81 in the past, which caused its black hole to light up. The galaxy was switched on.

"M81 is at a particularly crucial stage in development," Dr Puchnarewicz said.

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