Black hole gas rings flow in complex formations

The black hole "donut" is not actually a rigid structure.

The black rings of gas surrounding active supermassive black holes are not simple donut shapes, but a complex collection of highly dynamic gaseous components that flow like water formations.

National Astronomical Observatory of Japan (NAOJ) found gas expelled from the centre interacts with infalling gas to create a dynamic circulation pattern, similar to a water fountain in a city park.

Takuma Izumi at the NAOJ: “By investigating the motion and distribution of both the cold molecular gas and warm atomic gas with ALMA, we demonstrated the origin of the so-called donut structure around active black holes. Based on this discovery, we need to rewrite the astronomy textbooks.”

Izumi led a team that used the Atacama Large Millimeter/submillimeter Array to observe the supermassive black hole in the Circinus Galaxy located 14 million light years from Earth. The team then compared their observations to a computer simulation of gas falling towards a black hole made with the Cray XC30 ATERUI supercomputer.

Cold molecular gas falling towards the black hole forms a disk near the place of rotation; this gas is heated until the molecules break down into the component atoms and ions. Some of these atoms are then expelled above and below the disk, rather than being absorbed by the black hole. This hot atomic gas falls back onto the disk, creating a turbulent three-dimensional structure.

Keiichi Wada, a theoretician at Kagoshima University and leader of the study, said: “Previous theoretical models set a priori assumptions of rigid donuts. Rather than starting from assumptions, our simulation started from the physical equations and showed for the first time that the gas circulation naturally forms a donut. Our simulation can also explain various observational features of the ecosystem.

NAOJ’s work was published in The Astrophysical Journal.