Black hole donuts: scientists discover that they are actually gas fountains

Black hole donuts: scientists discover that they are actually gas fountains

Scientists have discovered that the ‘black hole donuts’ around supermassive black holes are actually more akin to fountains of gas.

The discovery is based on computer simulations and observations from the Atacama Large Millimeter/submillimeter Array (ALMA). The black hole donuts are actually rings of gas surrounding active supermassive black holes which have a dynamic circulation pattern similar to a fountain.

The black hole donut

Keiichi Wada, a theoretician at Kagoshima University in Japan, who lead the simulation study and is a member of the research team, 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 system.”

How scientists discovered the gas fountains

Takuma Izumi, who is a researcher at the National Astronomical Observatory of Japan (NAOJ), led a team of astronomers to observe the supermassive black hole in the Circinus Galaxy located 14 million light-years away from the Earth in the direction of the constellation Circinus. The team their observations with the computer simulation of gas falling towards a black hole made with the Cray XC30 ATERUI supercomputer operated by NAOJ.

They found that the black hole donut is not actually a rigid structure, but a complex collection of highly dynamic gaseous components.

ALMA image of the gas around the supermassive black hole in the center of the Circinus Galaxy. The distributions of CO molecular gas and C atomic gas are shown in orange and cyan, respectively. Credit: ALMA (ESO/NAOJ/NRAO), Izumi et al.

Rewriting the astronomy textbooks

Some supermassive black holes actively swallow material. Astronomers had previously believed that the matter builds up around the black hole in a donut structure instead of falling directly into the black hole.

Izumi added: “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.”

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