Astrophysicist Karl Gebhardt made international headlines in late November with the discovery of the largest black hole in the universe, a behemoth that's 17 billion times heavier than the Sun. Gebhardt and his colleagues found the black hole using the Hobby-Eberly Telescope at McDonald Observatory. The unusual black hole makes up 14 percent of its galaxy's mass, rather than the usual 0.1 percent. It's the third time UT scientists and equipment have discovered what, at the time, was the largest known black hole in the universe.
This galaxy, NGC 1277, and several more in the same study could change theories of how black holes and galaxies form and evolve. "The mass of this black hole is much higher than expected," Gebhardt said. "It leads us to think that very massive galaxies have a different physical process in how their black holes grow."
The study appeared in the journal Nature on Nov. 29 and garnered several headlines in mainstream media during subsequent days, including an interview with National Public Radio's Robert Siegel, excerpted here:
ROBERT SIEGEL, HOST: Astrophysicists evidently have their own chicken and egg problem. Which came first, the galaxy or the black hole? In reading up on the latest black hole discovery, I've learned that recently the smart money has been on the galaxy. But the new discovery evidently adds weight to the argument that the black hole may have come first. The discovery is a giant black hole in a tiny galaxy.
It was spotted by an international team of astrophysicists. And joining us now from Austin, Texas, at the University of Texas, is professor Karl Gebhardt. Welcome to the program and congratulations on this discovery.
KARL GEBHARDT: Thank you. It's very nice to be here.
SIEGEL: I gather that a galaxy typically comes with a black hole and vice versa. What's so unusual about this black hole that you've spotted?
GEBHARDT: Right. So every galaxy typically comes with a black hole, but in this one, the mass of this black hole is about 100 times larger than what we had expected based on the typical galaxy.
SIEGEL: So how does this change whatever theoretical ideas there are about the creations of galaxies and black holes and which one comes first?
GEBHARDT: Right. So the general consensus is exactly as you said. You start with a galaxy. There's a lot of stuff in a galaxy. There's lots of gas and dust. That stuff will interact with itself and it will fall into the middle. If there is a black hole, the gas and dust will go into the black hole and feed the black hole and grow its mass. And this leads to a really nice theoretical prediction that there's a correlation between the amount of mass in the black hole and the amount of mass in the galaxy.
Read on for more coverage of the discovery.
Huffington Post: Astronomers Discover Largest Black Hole in the Universe
Los Angeles Times: Gargantuan Black Hole Baffles Scientists
Discovery News: Small Galaxy Packs Black Hole Whopper
Austin American-Statesman: UT Astronomers Discover What Might Be Largest Black Hole in Universe
Houston Chronicle: Black Hole Discovery Puzzles UT Astronomers