The "color" of X-rays from the vicinity of the black hole, precisely measured by the X-ray astronomical satellite XRISM. The wavelengths are stretched, and the colors are changed due to general relativistic effects. (Top Right) An image of the jet obtained by the Global Millimeter VLBI Array at a wavelength of 3 mm. (Bottom) An artist's impression of the environment around a rapidly feeding supermassive black hole. The cold, flat accretion disk truncates at roughly 20 times the black hole's radius, transitioning into a hot accretion flow inside of which the jet is launched.
Image Credit: ©Tohoku University
Scientific Frontline: Extended "At a Glance" Summary: Supermassive Black Hole Jet Formation
The Core Concept: Supermassive black holes that rapidly consume matter can launch powerful streams of relativistic plasma (jets) into space, a phenomenon previously thought to be prevented by the formation of cold, flat accretion disks.
Key Distinction/Mechanism: A research team discovered that the cold accretion disk surrounding the active galaxy 3C 120 truncates at approximately 20 times the black hole's radius. Beyond this truncation point, the matter transitions into a hot plasma flow reaching hundreds of millions of degrees, which allows magnetic fields to accumulate and extract the black hole's rotational energy to launch the jet.
Major Frameworks/Components:
- Active Galaxy 3C 120: A galaxy located in the Taurus constellation that hosts a rapidly feeding supermassive black hole with a powerful relativistic jet.
- Accretion Disk Truncation: The physical point where the flat, cold disk of matter orbiting the black hole ends and transitions into a much hotter plasma state.
- General Relativity: Used to measure the distortion of an iron emission line from the accretion disk, allowing researchers to calculate how close the disk extends toward the black hole.
- Magnetic Field Extraction: The theoretical mechanism where accumulated magnetic fields in the hot plasma flow extract rotational energy from the black hole to channel matter into a jet.
- XRISM (X-Ray Imaging and Spectroscopy Mission): The state-of-the-art X-ray observatory used to detect the iron emission line and observe the hot plasma.
- Radio Astronomy Networks: The Global Millimeter VLBI Array, Very Long Baseline Array, and East Asian VLBI Network were used to trace the jet back to its origin.
Branch of Science: Astrophysics, Radio Astronomy, X-Ray Astronomy
Future Application: The findings provide a framework for future coordinated observations of more massive black holes using XRISM and global radio observatories, which will be compared with theoretical models and computer simulations to build a complete picture of matter, magnetic fields, and black hole rotation.
Why It Matters: Understanding how relativistic jets form in extreme environments helps explain how supermassive black holes influence the evolution of galaxies and the larger structural development of the universe.
Some supermassive black holes rapidly consume surrounding matter while simultaneously firing powerful streams of plasma into space at nearly the speed of light. However, this creates a physical puzzle: rapid feeding is expected to form a cold, flat accretion disk around the black hole, which prevents powerful jets from forming.
A research team led by Associate Professor Hirofumi Noda of Tohoku University and Associate Professor Kazuhiro Hada of Nagoya City University has now found evidence that helps resolve this mystery. By combining observations from the X-Ray Imaging and Spectroscopy Mission (XRISM) with international networks of radio and millimeter telescopes, the team identified the conditions that allow a rapidly feeding supermassive black hole to launch a powerful relativistic jet.
"By looking at the same black hole with state-of-the-art X-ray and radio telescopes, we were able to see both the hot plasma surrounding the black hole and the jet emerging from it," says Noda. "This allows us to directly connect the extreme environment near the black hole with the formation of the jet."
The team observed 3C 120, an active galaxy located in the constellation Taurus that hosts a supermassive black hole rapidly accreting matter while launching a powerful jet. XRISM detected an iron emission line from the accretion disk surrounding the black hole. The shape of this line is distorted by the effects of Einstein's general relativity, allowing the researchers to determine how close the disk extends toward the black hole.
The observations indicate that the cold, relatively flat accretion disk ends at about 20 times the black hole's radius. Beyond this point, it transitions into a hot flow of plasma reaching hundreds of millions of degrees. At the same time, radio and millimeter observations using the Global Millimeter VLBI Array, Very Long Baseline Array, and East Asian VLBI Network traced the narrowing jet back to its origin within this hot flow, close to the black hole.
This hot environment can allow magnetic fields to accumulate around the black hole. These magnetic fields are thought to extract some of the rotational energy of the black hole and channel it into a powerful jet. The observations therefore demonstrate that 3C 120 satisfies the conditions required for this mechanism to operate, providing new insight into how rapidly feeding supermassive black holes can produce relativistic jets.
The findings also offer a new way to study the immediate surroundings of supermassive black holes. The team is conducting further coordinated observations of a more massive black hole using XRISM and global radio observatories, while comparing the results with theoretical models and computer simulations.
"Our next goal is to build a more complete picture of how matter, magnetic fields, and black hole rotation interact in these extreme environments," adds Noda. "Understanding this process may also help us better understand how supermassive black holes influence the evolution of galaxies and the larger structures of the universe."
Published in journal: The Astrophysical Journal Letters
Title: Disk Truncation Triggers Relativistic Jet Launching of a Highly Accreting Supermassive Black Hole
Authors: Hirofumi Noda, Kazuhiro Hada, Hiroto Maruyama, Taishu Kayanoki, Kenji Toma, Taiki Kawamuro, Yoshiyuki Inoue, Tomohisa Kawashima, Soyeon Yeo, Ilje Cho, Keiichi Asada, Yasushi Fukazawa, and Yoshihiro Ueda
Source/Credit: Tohoku University
Edited by: Scientific Frontline
Reference Number: asph102026_01