London, July 15 (ANI): New simulations have revealed that turbulence created by jets of material ejected from the disks of the Universe’s largest black holes is responsible for halting star formation.

The simulations have been made by Evan Scannapieco, an assistant professor in the School of Earth and Space Exploration in the College of Liberal Arts and Sciences at Arizona State University (ASU) and Professor Marcus Brueggen of Jacobs University in Bremen, Germany.

Researchers have long known that the gas in the centres of some galaxy clusters is rapidly cooling and condensing, but were puzzled why this condensed gas did not form into stars.

Until recently, no model existed that successfully explained how this was possible.

At the core of each of these clusters is a black hole, billions of times more massive than the Sun.

Some of the cooling medium makes its way down to a dense disk surrounding this black hole, some of it goes into the black hole itself, and some of it is shot outward.

X-ray images clearly show jet-like bursts of ejected material, which occur in regular cycles.

As to why were these outbursts so regular, and why did the cooling gas never drop to colder temperatures that lead to the formation of stars, some unknown mechanism was creating an impressive balancing act.

“It looked like the jets coming from black holes were somehow responsible for stopping the cooling, but until now no one was able to determine how exactly,” said Scannapieco.

Scannapieco and Brueggen used the enormous supercomputers at ASU to develop their own three-dimensional simulation of the galaxy cluster surrounding one of the Universe’s biggest black holes.

By adapting an approach developed by Guy Dimonte at Los Alamos National Laboratory and Robert Tipton at Lawrence Livermore National Laboratory, Scannapieco and Brueggen added the component of turbulence to the simulations, which was never accounted for in the past.

Turbulence works in partnership with the black hole to maintain the balance.

Without the turbulence, the jets coming from around the black hole would grow stronger and stronger, and the gas would cool catastrophically into a swarm of new stars.

When turbulence is accounted for, the black hole not only balances the cooling, but goes through regular cycles of activity.

“When you have turbulent flow, you have random motions on all scales,” explained Scannapieco. “Each jet of material ejected from the disk creates turbulence that mixes everything together,” he added.

Scannapieco and Brueggen’s results reveal that turbulence acts to effectively mix the heated region with its surroundings so that the cool gas can’t make it down to the black hole, thus preventing star formation. (ANI)