Supersonic Gas Streams Left Over from The Big Bang Drive Massive Black Hole Formation

Theoretical studies have suggested these black holes formed from remnants of the first generation of stars, or from a direct gravitational collapse of a massive primordial gas cloud. However, these theories either have difficulty in forming super-massive black holes fast enough, or require very particular conditions.

Yoshida and JSPS Overseas Research Fellow Shingo Hirano, currently at the University of Texas at Austin, identified a promising physical process through which a massive black hole could form fast enough. The key was incorporating the effect of supersonic gas motions with respect to dark matter.

This is the gas density distribution around the new-born protostar. The left-to-right supersonic gas motion results in the non-spherical, compressed density structure. The collapsed inner cloud also shows the turbulated object, which can rapidly accrete onto the central protostar and cause a fast mass growth of it.

Credit:  Shingo Hirano
 

The team’s super-computer simulations showed a massive clump of dark matter had formed when the universe was 100 million years old. Supersonic gas streams generated by the Big Bang were caught by dark matter to form a dense, turbulent gas cloud. Inside, a protostar started to form, and because the surrounding gas provided more than enough material for it to feed on, the star was able to grow extremely big in a short amount of time without releasing a lot of radiation.

“Once reaching the mass of 34,000 times that of our Sun, the star collapsed by its own gravity, leaving a massive black hole. These massive black holes born in the early universe continued to grow and merge together to become a supermassive black hole,” said Yoshida.

This the evolution of the temperature and density structure in the protostellar accretion phase after the protostar formation. The rapid accretion of dense gas cloud (white contour) constricts an expansion of the photoionized region (red) which is possible to shut off the gas accretion.

Credit: Takashi Hosokawa
 

“The number density of massive black holes is derived to be approximately one per a volume of three billion light-years on a side – remarkably close to the observed number density of supermassive black holes,” said Hirano.

The result from this study will be important for future research into the growth of massive black holes. Especially with the increased number of black hole observations in the far universe that are expected to be made when NASA’s James Webb Space Telescope is launched next year.

This research was published in Science on September 28.

Aterui, one of the supercomputers this work used, is operated by the Center for Computational Astrophysics (CfCA) of the National Astronomical Observatory of Japan (NAOJ).

 

 

Contacts and sources:

Motoko Kakubayashi 

 Kavli Institute for the Physics and Mathematics of the Universe