CAPE CANAVERAL, FLORIDA – A black hole 12 billion times more massive than the sun has been found in a glowing quasar that existed when the universe was just a fraction of its current age, scientists said on Wednesday.
The discovery challenges currently held theories that black holes and their host galaxies grew in relative lock step over the eons.
Black holes are so massive that not even light can travel fast enough to escape their gravitational pits. Black holes are detected by effects they have on surrounding galaxies, stars and dust. Quasars, the most luminous objects in the universe, are distant galaxies with powerful jets of radiation and matter shooting out from discs of dust and gas spiraling into a central black hole.
The newly found black hole contains the equivalent of about 12 billion suns, more than twice the mass of previously found black holes of similar age, said researcher Bram Venemans with the Max Planck Institute for Astronomy in Germany.
By comparison, the black hole lurking at the center of the Milky Way galaxy has about 4 million to 5 million times the mass of the sun.
Scientists cannot explain how the newly found black hole grew so quickly. Theoretically, it could not have fed off surrounding gas as fast and as long as it would have needed to reach its massive size under currently understood laws of physics.
Many scientists have long believed the growth rate of black holes was limited. Black holes grow, scientific theory suggests, as they absorb mass. However, as mass is absorbed, it will be heated, creating radiation pressure that pushes the mass away from the black hole.
“Basically, you have two forces balanced together, which sets up a limit for growth, which is much smaller than what we found,” said Fuyan Bian of the Research School of Astronomy and Astrophysics at Australian National University (ANU).
Lead researcher Xue-Bing Wu, from Peking University in Beijing, wrote in an email: “Our discovery presents a serious challenge to theories about the black hole growth in the early universe. It may require either very special ways to grow the black hole within a very short time or the existence of a huge seed black hole when the first generation stars and galaxies formed. Both are difficult to be explained by the current theories.”
Another option is that two massive black holes in the early universe collided, forming an even larger black hole, Venemans said.
Clues may come from the quasar itself, which is glowing brightly enough to illuminate interstellar matter between itself and telescopes on and orbiting Earth. Ancient quasars may provide information about how stars formed in the early universe.
The black hole was discovered by a team of global scientists led by Wu as part of the Sloan Digital Sky Survey, which provided imagery data of 35 percent of the Northern Hemisphere’s sky.
The ANU is leading a comparable project, known as SkyMapper, to carry out observations of the Southern Hemisphere’s sky.
Bian expects more black holes to be observed as the project advances.
The research is published in this week’s issue of the journal Nature.
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