27 agosto 2015
Astrophysicists have found two supermassive black holes in Markarian 231, the nearest quasar to Earth. The discovery of two supermassive black holes — one larger one and a second, smaller one — are evidence of a binary black hole and suggests that supermassive black holes assemble their masses through violent mergers.
http://www.sciencedaily.com/releases/2015/08/150827154503.htm
