A rare moment of calm could give astronomers their first glimpse of a hungry black hole gorging on stars at the centre of our galaxy.
Scientists have long believed that the giant supermassive black hole dominates the middle of the Milky Way. But the “glare” from other energetic objects in the area has blocked their view.
Now a space telescope has managed to observe galactic central point on a rare occasion when several of the noisiest sources had faded into temporary silence.
Astronomers say the moment of calm is giving them the chance to probe for even fainter objects than usual and may allow them to see material streaming into the black hole.
The European Space Agency’s observatory Integral, which looks at the heavens with ganmma-ray eyes, has been peering through clouds of dust to study our galaxy’s central bulge. The region, in the constellation of Sagittarius, is one of the most dynamic in the galaxy and thought to be home to a gigantic black hole called Sagittarius A*.
Integral has been watching the area for nearly two years and has discovered several new sources of high-energy radiation near the galactic centre. They have mainly been X-ray binary stars – double stars where a normal star is in orbit around a star that has collapsed into a super-dense white dwarf, neutron star or even a black hole. As gas is stripped away from the normal star by its violent companion, it is heated to over a million degrees C, causing it to send out high-energy X-rays and gamma rays.
By chance, around ten of the noisy sources all fell quiet at around the same time, allowing better observations of the centre to be carried out. Chief ESA scientist Erik Kuulkers rules out the possibility that a mysterious external force calmed the objects at the same time. He said: “All the sources are variable and it was just by accident or sheer luck that they had turned off during that observation.”
The astronomers are now sifting through observations collected during the period of calm to see if the giant black hole reveals itself. Picture: An Integral image of the galaxy’s centre.