Universe Today
ESA's Integral spacecraft has released a new survey of the sky, seen in gamma rays - the most energetic radiation we know of. This latest survey brings the total sky coverage to 70%.
Integral has been producing this survey for 3 years now. During its first year, the spacecraft focused mainly on objects near the centre of the Milky Way, and turned up about 120 source. Now into its third year, the spacecraft has uncovered a total of 421 gamma ray sources.
Each of these sources are probably exotic binary objects, like black holes neutron stars, or actively feeding supermassive black holes. But about a quarter of these sources are totally unexplained. Astronomers have a few theories, like they're star systems shrouded in dust, or a rare class of objects called cataclysmic variable stars.
ESA News Release
