Supermassive Black Hole Twins

With the help their new studies astronomers discovered the second monster black hole at the center of the galaxy, called Markarian 739, which is about 425 million light-years from Earth, located in the constellation Leo, and which presence was revealed in observations by NASA’s Swift satellite and the Chandra X-Ray Observatory.The two black holes are separated by about 11,000 light years, which is about one-third the distance between our Solar System and the center of the Milky Way.Both black holes are intensely active and classified as supermassive.Stellar black holes, formed by the collapse of massive stars, typically have up to 10 or 20 times the mass of the sun.  

This two giant black holes at the center of Markarian 739,  which  is  also  known   by the name NGC 3758, are not the first monster black hole twins seen by astronomers, and they’re not the closest either. Both records are held by the galaxy NGC 6240, a galaxy that is about 330 million light-years from Earth.
source:www.space.com