Feasting on the Cosmos: The Strange Foods of Black Holes

An imaginary diagram of the interstellar medium distribution of active galactic nuclei based on current observational results. High-density molecular gas from the galaxy flows along the surface of the disk toward the black hole. The energy generated by the high temperature of the material accumulated around the black hole breaks apart the molecular gas and transforms it into atoms and plasma. Most of these multiphase interstellar materials are jets flowing outward from the galactic center (usually plasma jets are directly above the disk, and mostly atomic and molecular jets are diagonal). However, we find that most of the particles return to the disk like a spring. Credit: ALMA (ESO/NAOJ/NRAO), T. Izumi et al.

Recent advances in astrophysics have led to groundbreaking observations of gas flows surrounding supermassive black holes. These observations, made in an extraordinary detail light-year scale, revealing important insights into the behavior of these cosmic giants. Notably, the researchers discovered that while a significant amount of gas is transported into these black holes, only a small fraction – about 3 percent – is actually consumed. The rest of the gas is ejected and then recycled back into the host galaxy.

Not everything falls into a black hole absorbed, some of it is released as outflows. But the ratio of matter that is “eaten” by the black hole, and the amount that “falls out” is difficult to measure.

An international research team led by Takuma Izumi, an assistant professor at the National Astronomical Observatory of Japan, used the Atacama Large Millimeter/submillimeter Array (ALMA) to observe the supermassive black hole in the Circinus Galaxy, located 14 million light-years away in the direction of the constellation Circinus. This black hole is known to be actively feeding.

The Central Region of the Circinus Galaxy Observed With ALMA

The central region of the Circinus Galaxy observed with ALMA. Carbon monoxide (CO; indicating the presence of medium-density molecular gas) is shown in red; atomic carbon (C; indicates the presence of atomic gas) in blue; hydrogen cyanide (HCN; indicates the presence of high density molecular gas) in green; and the hydrogen recombination line (H36α; indicating the presence of ionized gas) in pink. The size of the central dense gas disk (green) is approximately 6 light-years. The plasma flow travels almost perpendicular to the disk. Credit: ALMA (ESO/NAOJ/NRAO), T. Izumi et al.

ALMA’s Role in Unraveling the Mysteries of Black Holes

Thanks to ALMA’s high resolution, the team is the first in the world to measure the amount of inflow and outflow to a scale of several light-years around the black hole. By measuring the flow of gases in different states (molecular, atomic, etc.) plasma) the team was able to determine the overall efficiency of black hole feeding and found it to be only about 3 percent. The team also confirmed that gravitational instability drives the flow.

The analysis also shows that most of the ejected flows are not strong enough to escape the galaxy and dissipate. They are recycled back into the circumnuclear regions around the black hole, and begin to slowly fall into the black hole again.

Reference: “Supermassive black hole feeding and feedback observed at subparsec scales” by Takuma Izumi, Keiichi Wada, Masatoshi Imanishi, Kouichiro Nakanishi, Kotaro Kohno, Yuki Kudoh, Taiki Kawamuro, Shunsuke Baba, Naoki Matsumoto, Yutaka Fujita and Konrad RW Tristram, . November 2023, Science.
DOI: 10.1126/science.adf0569

The study was funded by the National Astronomical Observatory of Japan and the Japan Society for the Promotion of Science.

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Image Source : scitechdaily.com

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