The oldest black hole ever discovered is so large that it cannot be explained.
This active supermassive black hole, or quasar, has a mass of 1.6 billion suns and lies at the heart of a galaxy more than 13 billion light years from Earth. The quasar, named J0313-1806, dates back to when the universe was only 670 million years old, or about 5 percent of the current age of the universe. This makes J0313-1806 twice as heavy and 20 million years older than the last record holder for the earliest known black hole (SN: 06.12.17).
Finding such a large, supermassive black hole so early in the history of the universe challenges astronomers’ understanding of how these cosmic beasts came to be. The researchers reported at a virtual meeting of the American Astronomical Society on Jan. 12 and in an article published Jan. 8 on arXiv.org.
It is believed that supermassive black holes grow out of smaller black holes that devour matter. However, astronomer Feige Wang of the University of Arizona and colleagues calculated that even if the seed of J0313-1806 had formed right after the first stars in the universe and had grown as quickly as possible, a launch mass of at least 10,000 suns would have been required . The normal way black holes form – through the collapse of massive stars – can only make black holes up to a few thousand times as massive as the sun.
A gigantic black hole made of seeds could have formed as a result of the direct collapse of large amounts of original hydrogen gas, says study co-author Xiaohui Fan, also an astronomer at the University of Arizona in Tucson. Or maybe the seed of J0313-1806 started small and formed through star collapse, and black holes can grow much faster than scientists think. “Both possibilities exist, but neither has been proven,” says Fan. “We have to look much earlier [in the universe] and look for much less massive black holes to see how these things grow. “