Astronomers see black hole flung from galaxy

A mysterious object in a distant galaxy spotted by an astronomy student may be a supermassive – or unusually heavy – black hole being flung out of its parent galaxy at high speed, scientists say. A new paper by an international team using data collected by Nasa suggests that the object - dubbed CXO J122518.6+144545 - may have been formed when two smaller black holes collided.

Marianne Heida of Utrecht university, one of the co-authors, made the initial discovery as an undergraduate, comparing hundreds of thousands of sources of X-rays picked up by the Chandra space observatory with the known positions of millions of galaxies.

Most galaxies are thought to have a supermassive black hole lying at their centre – but with a mass equivalent to more than one billion suns, it seems surprising to find one being ejected at speed from a galaxy. However, supercomputer models suggest that when two smaller holes merge, the direction and speed in which they are rotating can determine the path taken by the resultant supermassive black hole.

Speaking about her discovery (pictured above, in the red circle), Heida said her team suspect they have found further examples of the same phenomenon. "We have found even more of this strange class of X-ray sources," she said. "However, for these objects we first of all need accurate measurements from NASA's Chandra satellite to pinpoint them more precisely."

The scientists say there are other possible explanations for CXO J122518.6+144545. It could be a Type IIn supernova or what is known as a ULX (Ultra Luminous X-ray source) with an optical counterpart – which would have a range of possible explanations.

As an undergrad, Heida noticed a point of light in one of the galaxies mapped by Nasa which was incredibly bright – bright enough for a supermassive black hole – and yet not positioned at the centre of its galaxy. In the future, scientists hope to watch the actual process of black holes merging to form supermassive black holes. ·