Verifying the rotation of a supermassive black hole – Einstein’s theory of general relativity shines

Schematic representation of the tilted accretion disk model. The black hole’s spin axis is supposed to be straight up and down in this illustration. The direction of the jet points approximately perpendicular to the plane of the disc. The misalignment between the black hole’s spin axis and the disc’s spin axis causes the disc to spin and jet. Credit: Yuzhou Cui et al. (2023), Intouchable Lab@Openverse and Zhejiang Lab

Galaxy M87 Black hole It shows an oscillating jet, confirming its rotation, as concluded from a two-decade-long study that aligns with predictions of Einstein’s general theory of relativity.

The nearby radio galaxy M87, located 55 million light-years from Earth and containing a black hole 6.5 billion times larger than the Sun, shows an oscillating flow that oscillates up and down with an amplitude of about 10 degrees, confirming the existence of the black hole. wraps.

The study, headed by Chinese researcher Dr. Yuzhou Cui, was published in nature On September 27, it was conducted by an international team using a global network of radio telescopes.

Through extensive analysis of telescope data from 2000 to 2022, the research team revealed an 11-year recurring cycle in the precession of the jet’s base, as predicted by Einstein’s theory of general relativity. The study links the flow dynamics to the central supermassive black hole, providing evidence that the black hole in M87 is rotating.

Supermassive black hole phenomena

Supermassive black holes at the center of active galaxies – the most unstable celestial bodies in our universe – can accumulate huge amounts of matter due to their extraordinary gravitational force and gravitational force. plasma The outflows, known as jets, approach the speed of light and extend thousands of light-years across.

The mechanism of energy transfer between supermassive black holes and their accretion disks and relativistic jets has puzzled physicists and astronomers for more than a century. The prevailing theory suggests that energy could be extracted from a rotating black hole, allowing some of the material surrounding the supermassive black hole to be ejected with significant energy. However, the spin of supermassive black holes, a crucial factor in this process and the most important parameter other than the black hole mass, has not been directly observed.

Top panel: M87 jet structure at 43 GHz based on semiannual stacking data observed from 2013 to 2018. White arrows indicate the jet position angle in each subplot. Bottom panel: Best fitted results based on the annually stacked image from 2000 to 2022. The green and blue dots were obtained from observations at 22 GHz and 43 GHz, respectively. The red line represents the best fit according to the initiative model. Credit: Yuzhou Cui et al., 2023

Focus on M87

In this study, the research team focused on M87, where the first observational astrophysical jet was observed in 1918. Thanks to its proximity, the jet formation regions near the black hole can be resolved in detail using very long baseline interferometry (VLBI). It is also represented by imaging of the modern black hole’s shadow using the Event Horizon Telescope (EHT). By analyzing VLBI data from M87 acquired over the past 23 years, the team detected periodic precursor jets at its base, providing insight into the state of the central black hole.

Black hole dynamics and relativity

At the heart of this discovery lies the crucial question: What force in the universe could change the direction of such a powerful jet? The answer could be hidden in the behavior of the accretion disk, a formation associated with the central supermassive black hole.

As the falling material orbits the black hole due to its angular momentum, it forms a disk-like structure before gradually spiraling inward until it is fatefully pulled into the black hole. However, if a black hole is rotating, it exerts a significant influence on the spacetime surrounding it, causing nearby objects to be pulled along its axis of rotation, a phenomenon known as “frame drag,” which was predicted by Einstein’s general theory of relativity.

The research team’s comprehensive analysis suggests that the rotation axis of the accretion disk deviates from the black hole’s rotation axis, leading to a pre-jet. The detection of this motion provides unambiguous evidence that the supermassive black hole in M87 is indeed rotating, enhancing our understanding of the nature of supermassive black holes.

“We are pleased with this important result,” said Yuzhou Cui, a postdoctoral researcher at Zhejiang Laboratory, a research institution in Hangzhou, and lead author of the study. “Because the misalignment between the black hole and the disk is relatively small and the precession period is about 11 years, high-resolution data collection tracking the structure of M87 over two decades and comprehensive analysis is necessary to obtain this breakthrough.”

Dr. Kazuhiro Hada of the National Astronomical Observatory of Japan added: “After successfully imaging the black hole in this galaxy using EHT, whether this black hole is rotating or not has become a major concern among scientists.” “Now anticipation has turned into certainty. This monstrous black hole is already spinning.”

Future contributions and implications

This work made use of a total of 170 epochs of observations acquired by the East Asia VLBI Network (EAVN), the Very Long Baseline Array (VLBA), the Joint Array of KVN and VERA (KaVA), and the global East Asia to Italy (EATING) network. In total, more than 20 telescopes from around the world contributed to this study.

China’s radio telescopes also contributed to this project, including China’s 65-meter Tianma radio telescope with its huge dish and high sensitivity to millimeter wavelengths. In addition, a 26-meter radio telescope in Xinjiang improves the angular resolution of EAVN observations. High-quality data with high sensitivity and high angular resolution are essential to obtain this achievement.

“The 40-meter Shigatse radio telescope at the Shanghai Astronomical Observatory will improve the EAVN’s millimeter imaging capability. In particular, the Tibetan Plateau, where the telescope is located, has one of the best site conditions for (sub-millimeter) wavelength observations,” said Prof. Zhiqiang Chen, Director of the Shanghai Astronomical Observatory of the Chinese Academy of Sciences, said: “It meets our expectations of strengthening domestic facilities for astronomical observation.”

While this study sheds light on the mysterious world of supermassive black holes, it also presents enormous challenges. The structure of the accretion disk and the exact spin of the M87 supermassive black hole are still largely uncertain. This work also predicts that there will be more sources with this configuration, posing a challenge for scientists to discover.

Reference: “The jet nozzle connecting to a rotating black hole in M87” by Yucho Kuei, Kazuhiro Hada, Tomohisa Kawashima, Motoki Kino, Weikang Lin, Yusuke Mizuno, Hyunwook Ru, Markei Honma, Kono Yi, Jintao Yu, Jongho Park, Wu Jiang , Zhiqiang Chen, Evgenia Kravchenko, Juan Carlos Algaba, Xiaoping Cheng, Eli Zhou, Gabriele Giovannini, Marcello Giroletti, Taehyun Jung, Ru Sin Lu, Kotaro Ninuma, Jungwan Oh, Ken Ohsuga, Satoko Sawada Satoh, Bong Won Son, Hiroyuki R. Takahashi, Meeko Takamura, Fumi Tazaki, Sasha Tripp, Kiyoaki Wajima, Kazunori Akiyama, Tao An, Keiichi Asada, Salvatore Botaccio, Do Young-byun, Lang Kui, Yoshiaki Hagiwara, Tomoya Hirota, Jeffrey Hodgson, Noriyuki Kawaguchi, Jae-Young Kim, Sang Song Lee, Ji-Won Lee, Jeong-Ee Lee, Giuseppe Maccaferri, Andrea Melis, Alexey Melnikov, Carlo Migoni, Si-Jin Oh, Koichiro Sugiyama, Xuezheng Wang, Yingkang Zhang, Zhong Chen, Jo-Yun Hwang, Dong-Kyu Jung, Heo-Ryung Kim , Jeong Suk Kim, Hideyuki Kobayashi, Bin Li, Guangwei Li, Xiaofei Li, Xiong Liu, Qinghui Liu, Xiang Liu, Chung Sik Oh, Tomoaki Aoyama, Duke Jiu Ruo, Jinqing Wang, Na Wang, Xiqiang Wang, Bo Xia, Hao Yan, Jae-hwan Yum, Yoshinori Yonekura, Jianping Yuan, Hua Zhang, Rongping Zhao, and Yi Zhong, September 27, 2023, nature.
doi: 10.1038/s41586-023-06479-6