A team of international scientists have investigated the birth of supermassive black holes in the early universe and found a new mechanism that might have triggered their formation: the rapid growth of dark matter halos.
The researchers used the Renaissance Simulations of the Blue Waters supercomputer in order to create a computer simulation of the early years of the universe. Their findings cast doubts on the long-accepted belief that the first supermassive black holes were formed in areas bombarded by radiation of nearby galaxies.
A paper on the formation of supermassive black holes in the early universe was published in the journal Nature.
The First Supermassive Black Holes
"In this study, we have uncovered a totally new mechanism that sparks the formation of massive black holes in particular dark matter halos," stated John Wise, an associate professor at Georgia Tech's School of Physics and an author of the paper.
Wise and his colleagues came to the conclusion while analyzing the computer simulation that traces back the early universe's evolution. From their analysis, they found 10 dark matter halos that should have formed stars because of their masses, but instead only had dense gas clouds.
They ran additional simulations on two halos, each was about 2,400 light-years across, at much higher resolutions to observe what might have happened in them about 270 million years after the Big Bang.
"It was only in these overly-dense regions of the universe that we saw these black holes forming," explained Wise. "The dark matter creates most of the gravity, and then the gas falls into that gravitational potential, where it can form stars or a massive black hole."
The Role Of Dark Matter Halos
The findings do not completely disprove that ultraviolet radiation from a nearby galaxy provides the perfect environment for supermassive black holes to form. The researchers add that it is still a factor.
However, the research suggests that ultraviolet radiation is not the dominant factor in the creation of the earliest supermassive black holes. Scientists should be considering how quickly the halos grow.
The team found that black holes were most likely to form in areas where these halos ballooned due to the mergers of gas clouds that build up a nascent galaxy.
Moreover, fast-growing halos might have been common throughout the history of the universe. The researchers predict that these halos might have been common enough to give birth to most supermassive black holes both in the early universe and in the present.
The team hopes that future research will use simulations to observe the lifecycle of supermassive black holes — beginning with their formation, growth, and evolution.