Sydney Morning Herald 
December 6, 2011
Scientists have discovered the two biggest black holes ever observed, each with a mass billions of times greater than the Sun’s, according to a study published on Monday.
The two giants are located in the heart of a pair of galaxies several hundred million light years from Earth, said the study in scientific journal Nature.
Each black hole is estimated to have a mass about 10 billion times greater than the sun, dwarfing the previously largest-known black hole, which has a mass of 6.3 billion suns.
The University of California, Berkeley, team led by Nicholas McConnell and Chung-Pei Ma said one black hole is located in NGC 3842, the brightest of a cluster of galaxies about 320 million light years from Earth.