2023-09-27 17:29:26
The spin axis of the black hole is assumed to be aligned vertically. The direction of the jet is almost perpendicular to the disk. -YUZHU CUI ET AL. 2023,
MADRID, 27 Sep. (EUROPA PRESS) –
The nearby radio galaxy M87, 55 million light years away, features an oscillating jet that oscillates up and down with an amplitude of about 10 degrees, which confirms the spin of the black hole.
The study, led by Chinese researcher Dr. Cui Yuzhu and published in the magazine ‘Nature’, It was carried out by an international team using a global network of radio telescopes.
Through an exhaustive analysis of data obtained by telescopes between 2000 and 2022, the research team revealed the existence of a recurring 11-year cycle in the precession movement of the base of the jet, as predicted by the General Theory of Einstein relativity. The study links the dynamics of the jet with the central supermassive black hole, offering evidence that the M87 black hole rotates.
Supermassive black holes located at the centers of active galaxies – the most disturbing celestial objects in our universe – can accumulate enormous amounts of material due to the extraordinary gravitational force and the power of plasma jets, known as jets, that are They approach the speed of light and extend thousands of light-years away.
The mechanism of energy transfer between supermassive black holes and their accretion disks and relativistic jets has baffled physicists and astronomers for more than a century. A prevailing theory suggests that energy can be extracted from a spinning black hole, which allows part of the material surrounding the supermassive black hole to be ejected with great energy.
However, the spin of supermassive black holes, a crucial factor in this process and the most fundamental parameter apart from the mass of the black hole, had not been directly observed.
In this study, the team of researchers focused on M87, where the first astrophysical jet was observed in 1918. Thanks to its proximity, the regions of jet formation near the black hole can be resolved in detail with very long baseline interferometry (VLBI), as represented by recent images of the black hole’s shadow obtained with the Event Horizon Telescope (EHT).
Analyzing VLBI data of M87 obtained over the past 23 years, the team detected the periodic precessional jet at its base, offering insight into the state of the central black hole.
When asked what force in the universe can alter the direction of such a powerful jet, the researchers point out that the answer could be hidden in the behavior of the accretion disk, a configuration related to the central supermassive black hole.
As the inflected materials orbit the black hole due to their angular momenta, they form a disk-like structure before gradually spiraling until they are fatally pulled toward the black hole.
However, if the black hole is spinning, it exerts a significant impact on the surrounding spacetime, causing nearby objects to be dragged along its axis of rotation, a phenomenon known as “frame creep”, which was predicted by Einstein’s General Theory of Relativity.
The exhaustive analysis of the research team indicates that the rotation axis of the accretion disk misaligns with the spin axis of the black hole, giving rise to a precessional jet. The detection of this precession provides unequivocal evidence that the M87 supermassive black hole is spinning, improving our understanding of the nature of supermassive black holes.
“We are delighted with this important finding,” said Yuzhu, a postdoctoral researcher at Zhejiang Lab, a research institution in Hangzhou, China, and lead author of the paper. “Given that the misalignment between the black hole and the disk is relatively small and precession period is about 11 years, accumulating high-resolution data mapping the structure of M87 over two decades and its exhaustive analysis are essential to obtain this achievement.
“Following the success of imaging black holes in this galaxy with the EHT, knowing whether this black hole is spinning or not has been a central concern among scientists,” adds Dr. Kazuhiro Hada of the National Astronomical Observatory of Japan. –. Now the expectation has become certainty. This monstrous black hole is indeed spinning.”
This work used a total of 170 epochs of observations obtained by the East Asian VLBI Network (EAVN), the Very Long Baseline Array (VLBA), the KVN and VERA ensemble (KaVA), and the East Asia to Italy Nearly Global network (EATING). In total, more than 20 telescopes around the world have contributed to this study.
China’s radio telescopes also contributed to this project, including the Chinese Tianma 65-meter radio telescope, with its huge dish antenna and high sensitivity at millimeter wavelengths.
In addition, the Xinjiang 26-meter radio telescope improves the angular resolution of EAVN observations. Good quality data with high sensitivity and high angular resolution They are essential to obtain this achievement.
“The 40-meter Shigatse radio telescope, built by the Shanghai Astronomical Observatory, will further enhance EAVN’s millimeter imaging capabilities,” said Professor SHEN Zhiqiang, Director of the Shanghai Astronomical Observatory of the Chinese Academy of Sciences. –.Especially, the Tibetan plateau, where the telescope is located, “It has one of the most excellent siting conditions for observations at (sub)millimeter wavelengths.”
“It meets our expectations of promoting national submillimeter facilities for astronomical observations,” he adds.
Although this study sheds light on the mysterious world of supermassive black holes, it also presents formidable challenges. The structure of the accretion disk and the exact value of the spin of the supermassive black hole M87 remain very uncertain. This work also predicts that there will be more sources with this configuration, which represents a challenge for scientists when it comes to discovering themthey conclude.
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