Astrophys. J 781, 59 (2014)

Mon. Not. R. Astron. Soc 435, 1904–1927 (2013)

Abell 1795 was an unremarkable star cluster in the northern constellation Boötes (the ploughman) until two teams of astrophysicists — led by Davide Donato and by Peter Maksym, respectively — independently found evidence for the aftermath of a star being ripped apart by a massive black hole. Such a 'tidal disrupture event' leads to stellar debris falling into the black hole. This in turn causes shock-heating and accretion onto the black hole, giving rise to a luminous X-ray or ultraviolet flare, believed to be brighter than a supernova. But as with many astrophysical phenomena, telescopes have to be looking at the right place at the right time.

Fortunately, the two teams were able to use archival data from many telescopes, in particular ESA's XMM-Newton and NASA's Chandra and the Extreme Ultraviolet Explorer (EUVE). By painstakingly corroborating data taken over 6–12 years from various telescopes, the teams managed to piece together what happened: about three months before the first EUVE observations, a standard star was sheared apart by an intermediate-mass black hole (105 solar masses) in a dwarf galaxy. Given that scant evidence exists for intermediate-mass black holes, theorized to be 'seeds' for supermassive black holes, this was a remarkable find indeed.