Behemoth Black Holes Were Born in Violent Galactic Collisions
If you want to make a supermassive black hole quickly, collide young, massive proto-galaxies. After running the numbers on a supercomputer, that’s what researchers have recently concluded. Their simulation shows that a collision between massive gas clouds could make a black hole “from scratch” in a relatively short time.
Supermassive black hole truly are super massive–possibly billions of times the mass of our sun. They also appear to be super old; some estimates say they formed less than a billion years after the Big Bang. Thus the puzzle, how do you get so big so quickly?
The paper which appeared online yesterday in Nature (with associated letter) modeled the collision of two gas clouds that formed into a unstable gas disk, which channeled gas into its center. Eventually this dense center collapsed in on itself to make the black hole king. (See simulations of the proto-galaxies colliding, above.)
“It has been perplexing how such black holes with masses billions of times the mass of the sun could exist so early in the history of the universe,” astronomer Julie Comerford of University of California Berkeley, who was not involved in the study, wrote in an e-mail to Wired.com. “These simulations are an important advance in understanding how those supermassive black holes were built up so quickly.” [Wired]
Since scientists believe that supermassive black holes are in the center of galaxies, their rapid formation may mean modification for current models of how galaxies form, too–with the supermassive black hole orchestrating the galaxy’s growth.
“Our result shows that big structures, both galaxies and massive black holes, build up quickly in the history of the universe,” said study co-author Stelios Kazantzidis, an astronomer at Ohio State University…. “In our model, the black hole grows much faster than the galaxy. So it could be that the black hole is not regulated at all by the growth of the galaxy. It could be that the galaxy is regulated by the growth of the black hole.” [Space.com]
Next the team hopes to refine their models. Said co-author Andrés Escala:
There are limitations to this model, however, says Escala. The simulation has some idealisations. “Reality is much more complex than what we are able to model with current supercomputers,” he says, “So the next step is to refine these idealisations and relax the initial conditions to make it more general.” [Nature]
To confirm or refute this model, astronomers also hope to take measurements of reality itself. In the future, the James Webb Space Telescope and the Atacama Large Millimeter Array (ALMA) may help researchers determine the mass of galaxies and their supermassive black hole cores, and NASA’s planned Laser Interferometer Space Antenna could pick up gravitational waves still rippling through space-time after these early universe collisions.
Images: Ohio State University