Astronomers discover two of the most massive black holes ever

Nature : Astronomers have discovered the two most massive black holes known in the universe to date, writes Ron Cowen for Nature. Using instruments on the Keck II and Gemini North telescopes on Hawaii’s Mauna Kea, Chung-Pei Ma (University of California, Berkeley) and colleagues found that a cluster galaxy called NGC 3842 houses a black hole with a mass equivalent to 9.7 billion Suns and that another galaxy, NGC 4889, has a black hole with an estimated mass of at least 20 billion Suns. The previous record holder has a mass of 6.7 billion Suns. The galaxies are about 300 million light-years from Earth—relatively close by cosmic standards. Because supermassive black holes formed early in the universe, the team’s findings, published this week in Nature, suggest that the two newly discovered black holes could represent a missing link to the brightest quasars from early cosmic times. Also, because of their unusually large mass, they may have evolved differently from smaller black holes.