Since they’re basically invisible, it can be hard to pin down just how big a black hole is. They can range anywhere from a few times the mass of the Sun up to millions or billions times that mass, but there’s a potential class that are even bigger than that.
A new study of data gathered by NASA’s Chandra X-ray telescope has found that these so-called “ultramassive” black holes may be larger and more common than we thought.
The smallest class is the stellar mass black holes, which can be from about five to 30 times the mass of the Sun. In the middle there sits a proposed group known as intermediate-mass black holes, between 100 and 10,000 solar masses. And finally there’s the heavyweights that lurk at the center of galaxies, supermassive black holes with masses of millions or even a few billion Suns.
But there’s quite a gap between a million and billion, leading some astronomers to claim that there should be another class at the top for the very biggest. These ultramassive black holes would include objects of tens of billions of solar masses, such as S5 0014+813, which contains one of the largest known black holes at about 40 billion solar masses.