Black Hole 'Donuts' Are Actually 'Fountains'

As it approaches the black hole, 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. These three components circulate continuously, similar to a water fountain in a city park.

 

Artist’s impression of the gas motion around the supermassive black hole in the center of the Circinus Galaxy. The three gaseous components form the long-theorized “donut” structure: (1) a disk of infalling dense cold molecular gas, (2) outflowing hot atomic gas, and (3) gas returning to the disk.

Credit: NAOJ

“Previous theoretical models set a priori assumptions of rigid donuts,” explains Keiichi Wada, a theoretician at Kagoshima University in Japan, who lead the simulation study and is a member of the research team. “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.”

 

Cross section of the gas around a supermassive black hole simulated with NAOJ’s supercomputer ATERUI. The different colors represent the density of the gas, and the arrows show the motion of the gas. It clearly shows the three gaseous components forming the “donut” structure.

Credit: Wada et al.

“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,” said Izumi. “Based on this discovery, we need to rewrite the astronomy textbooks.”

Paper and the research team

These observation results were published as T. Izumi et al. “Circumnuclear Multiphase Gas in the Circinus Galaxy. II. The Molecular and Atomic Obscuring Structures Revealed with ALMA” in the Astrophysical Journal in October 2018.

The research team members are:
Izumi Takuma (National Astronomical Observatory of Japan), Keiichi Wada (Kagoshima University / Ehime University / Hokkaido University), Ryosuke Fukushige (Kagoshima University), Sota Hamamura (Kagoshima University), and Kotaro Kohno (The University of Tokyo)

This research was supported by JSPS KAKENHI (Grant Numbers 17K14247, 16H03959, JP17H06130).

Contacts and sources:
National Astronomical Observatory of Japan

Citation:  “Circumnuclear Multiphase Gas in the Circinus Galaxy. II. The Molecular and Atomic Obscuring Structures Revealed with ALMA”
T. Izumi et al.、2018, Astrophysical Journal 867, 48. https://doi.org/10.3847/1538-4357/aae20b
https://alma-telescope.jp/en/news/press/agn-201811