First evidence of rotation of a supermassive black hole

2023-09-28 11:18:08

An international scientific team, with the participation of the Institute of Astrophysics of Andalusia (IAA-CSIC), has analyzed 23 years of data from the center of the Galaxia Messier 87 (M87)which houses a supermassive black hole (6.5 billion times more massive than the Sun), the first to be imaged.

Image of the black hole located in the center of the galaxy M87. /EHT

The results, published in Naturereveal that the jet that emerges from the black hole at very high speed swings up and down with an amplitude of about 10 degrees, which in turn confirms that the black hole is rotating.

The jet emerging from the black hole of the M87 galaxy at very high speed oscillates up and down with an amplitude of about 10 degrees, confirming that it rotates

Black holes absorb large amounts of material due to their gravitational force, so powerful that not even light escapes from them, and propel a plasma flow in the form of a jet It moves almost at the speed of light and covers enormous distances. The galaxy M87, for example, features a jet emerging from its central regions and extending far beyond the size of the galaxy itself.

However, the energy transfer mechanism between supermassive black holeslos accretion disks and the jets is still unknown. Prevailing theory suggests that energy can be extracted from a rotating black hole, allowing some of the material surrounding the black hole to be ejected at high speed. However, the rotation of supermassive black holes, a crucial factor in this process and the fundamental parameter besides black hole mass, has never been directly observed.

Oscillating or precessing jet

The research team’s analysis, which includes a comparison with a theoretical simulation of the latest generation, indicates that the axis of rotation of the accretion disk is misaligned with the axis of rotation of the black hole, which generates an oscillating jet, or in precession (like the swinging of a top).

The detection of this precession constitutes a unequivocal evidence that the M87 supermassive black hole is indeed spinning, opening up new dimensions in our understanding of the nature of these objects.

“Since the misalignment between the black hole and the disk is relatively small and the precession period is around eleven years, the accumulation of high-resolution data of the structure of M87 over two decades and comprehensive analysis have been essential to obtain this achievement,” he points out Yuzhu Cuiresearcher at the Zhejiang Laboratory (China) and lead author of the article.

As the misalignment between the black hole and the disk is small and the precession period is about 11 years, the accumulation of data from M87 over two decades and exhaustive analysis have been essential for this achievement.

Yuzhu Cui (Laboratorio de Zhejiang)

At the center of this discovery is the critical question: What force in the universe can alter the direction of such a powerful jet? The answer could lie in the behavior of the accretion disk: as infalling materials orbit the black hole, they form a disk structure before gradually spiraling until they are absorbed by the black hole.

However, if the black hole spins, it exerts a significant impact in space-time surrounding area, causing nearby objects to be dragged along their axis of rotation, that is, producing “frame drag” (frame dragging) predicted by Einstein’s General Relativity.

Global Telescope Network

“This work has analyzed a total of 170 epochs of observations obtained by the East Asia VLBI Network (EAVN), the Very Long Baseline Array (VLBA), the joint network of KVN and VERA (KaVA) and the East Asia to Italy network Nearly Global (Eating). In total, more than 20 telescopes and 45 institutions around the world have contributed to the study. Only close collaboration has allowed us to obtain these fascinating results,” he points out. Ilje Choresearcher at the Institute of Astrophysics of Andalusia (IAA-CSIC) who participates in the work.

While this study sheds light on how a supermassive black hole works, it also presents big unknowns. The structure of the disk and the exact value of the spin of the supermassive black hole M87 are still uncertain, and this work predicts that there are more factors involved in this configuration, which adds new challenges to the research.

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