PKS 0745 in 60 Seconds

Narrator (April Hobart, CXC): Some of the biggest black holes in the Universe may actually be even bigger than previously thought. This is according to a new survey of 18 of the largest known black holes using data from the Chandra X-ray Observatory and other telescopes. A group of astronomers studied black holes found in the centers of galaxy clusters that are filled with hot gas. They came up with the new estimates of the black hole masses by looking at the amount of X-rays and radio waves they generate. The researchers found that the black holes in the survey may be about ten times more massive than previously thought. This includes at least ten that could weigh between 10 and 40 billion times the mass of the sun, making them "ultramassive" black holes.