2023-11-11 11:40:08
A “supermassive black hole” exists at the center of many galaxies, and in the process of sucking in large amounts of gas, it radiates enormous amounts of energy. Analysis of the flow of matter toward a black hole on a scale smaller than a few tens of light years has not been well understood. A research team led by Takuma Izumi of the National Astronomical Observatory of Japan observed the center of the Compass Galaxy using the large radio interferometer “ALMA (Atacama Large Millimeter/Submillimeter Interferometer)” (Atacama Desert, Chile), and detected a black hole. We analyzed in detail the flow of gas flowing into the As a result, we succeeded in analyzing the material state and momentum of gases on an extremely small scale of regarding 1 light year. This is the highest resolution analysis of this type of research.[▲Figure 1: An imaginary drawing of the area around a black hole that reflects the results of this research. Plasma gas flows vertically away from the black hole, while molecular and atomic gases flow diagonally. It has also been revealed that this gas flow moves like a fountain returning to the accretion disk (Credit: ALMA (ESO/NAOJ/NRAO), T. Izumi et al.)]■ Around the black hole The details of the current situation are unknown.Almost all galaxies are known to have a “supermassive black hole” at their center. A black hole’s powerful gravity pulls in a large amount of matter, but because a black hole’s size is small compared to its gravitational strength, the attracted matter concentrates and creates a traffic jam. What is formed at this time is an “accretion disk” that orbits around the black hole. The materials in the accretion disk rub once morest each other, reaching temperatures of several million degrees Celsius, and emitting a huge amount of energy, mainly X-rays. Sometimes it is more than the combined radiation of all the stars in the galaxy, and galaxies with such active centers are called “active galaxies.” Because the energy radiation becomes more intense as you move toward the center, it is thought that some of the matter in the accretion disk does not fall into the black hole, but flies out on the radiation. The flow of matter to such black holes has been well analyzed both theoretically and observationally, from the scale of 100,000 light-years, which includes the entire galaxy, to the scale of several hundred light-years, which is the scale of the center of the galaxy. However, the density of matter extremely close to a black hole is high, making direct observation difficult. In addition, near a black hole, the speed and temperature of matter change drastically, and the movement also changes depending on whether the state of the material is molecules, atoms, or plasma. Analysis that takes these into account requires a huge amount of calculations, and it is difficult to consider it theoretically. For this reason, there are many mysteries regarding the movement of matter in units smaller than a few tens of light years, which are extremely close to a black hole, including the basic question of what proportion of matter is sucked into the black hole or escapes. Even I didn’t really understand. ■ Observing the detailed flow of gas with ALMA[▲Figure 2: False color image of the center of the Compass galaxy observed with ALMA. The molecular gases carbon monoxide (red) and hydrogen cyanide (green), the atomic gas carbon atoms (blue), and the plasma gas hydrogen (pink) are reflected (Credit: ALMA (ESO/NAOJ/NRAO) , T. Izumi et al.)]Izumi and his colleagues conducted observations with ALMA of the active galaxy “Compass Galaxy,” which is approximately 13 million light-years away from Earth, and detected gas within a few light-years of the galactic center. We observed the flow of As a result, they succeeded in observing the gas flow in a region of regarding 6 light years at the center with a resolution of regarding 1 light year, the highest resolution to date. The first observation was that light from the center of the galaxy was absorbed by molecular gas, creating a shadow. Detailed observations reveal that the molecular gas is moving away from the observer, which corresponds to falling toward the black hole at its center. We also obtained observations of the momentum of the observed gas accretion disk. The momentum of the gas disk generates pressure, which supports the gas disk’s gravity, but this observation result showed that the gravity is too large to be supported by pressure. In this state, the gas disk collapses under its own gravity and forms a complex structure, a state called “gravitational instability,” and the gas disk changes from orbiting around the black hole to falling. Masu. This research at ALMA is the first time that gravitational instability has been revealed through observational results. Furthermore, the gas flow in the center was quantitatively understood from the observation results of gas density and velocity. It has now been revealed that the amount of gas falling into a black hole, calculated from the intensity of radiation from active galaxies, is only 3% of the gas density and velocity revealed by ALMA observations. Ta. In other words, the black hole is “devouring” the falling gas, with most of it flying outward. So, how does that gas scatter? ALMA has clarified the details of gas by dividing it into three phases : molecules, atoms, and plasma. It was found that all gas phases escape from the black hole, and that the amounts of molecular gas and atomic gas are particularly large. It was also revealed that many of them are not fast enough to break through the black hole’s gravity and fly out, so they return to the accretion disk. In other words, ALMA revealed that there is a “fountain” of gas around a supermassive black hole. *…In this research, carbon monoxide and hydrogen cyanide were observed as molecular gases, carbon atoms were observed as atomic gases, and hydrogen was observed as plasma gas. ■A monumental achievement in the study of supermassive black holes The results of this observation revealed an extremely detailed picture of the flow of gas that occurs around supermassive black holes. The dynamics around supermassive black holes and the conditions under which they suck in matter and grow are still poorly understood, and it is said that they are involved in the evolution of galaxies themselves, so it is extremely difficult to understand the details. It is important. Mr. Izumi described this result as “a monumental achievement in the history of supermassive black hole research.” SourceTakuma Izumi, et al. “Supermassive black hole feeding and feedback observed on subparsec scales”. (Science) Takuma Izumi. “Finally elucidated! Growth mechanism of supermassive black holes and material circulation at the center of galaxies”. (ALMA) Written by Ayae Riri
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