This black hole flipped its magnetic field

A significant scientific discovery has emerged regarding the magnetic field surrounding the supermassive black hole in the M87 galaxy, approximately 55 million light-years away from Earth. Observations reveal that the magnetic field has undergone a dramatic reversal, challenging existing theories on black hole dynamics and providing new insights into the behavior of these enigmatic cosmic entities.

The black hole, referred to as M87*, was first brought to light through imaging in 2017, as detailed in previous publications. The groundbreaking images showcased a bright ring of plasma, known as the accretion disk, encircling this massive black hole. At that time, the observed properties of the disk, including the embedded magnetic field, conformed to theoretical expectations.

Recent studies focusing on the accretion disk have unveiled unexpected variability; research featured in an upcoming issue of Astronomy & Astrophysics indicates that the magnetic field has shown instability over the years. Notably, in 2018, the field experienced a notable shift and nearly vanished, leading to a complete reversal by 2021.

According to Chi-kwan Chan, a coauthor of the study and an astronomer at Steward Observatory in Tucson, “No theoretical models we have today can explain this switch.” The expectation was for the magnetic field configuration around such a massive entity—approximately 6 billion times the mass of the Sun—to maintain a degree of stability, particularly when compared to the supermassive black hole at the center of our own Milky Way galaxy.

The accretion disk serves as the initial phase for material that ventures into the black hole. As this matter is compressed under immense gravitational forces, it becomes superheated and emits X-rays and radio waves detectable by Earth-based telescopes. As the black hole itself does not emit light, studying the accretion disk remains one of the most effective methods for examining black holes.

In this comprehensive research, scientists dissected images of M87*’s accretion disk captured by the Event Horizon Telescope, an international network of radio telescopes. The team specifically investigated polarized light, a type of light whose waves oscillate in a fixed direction, to study the magnetic field’s orientation.

By analyzing the shifts in polarization patterns over consecutive years, the researchers established that the magnetic field around the black hole had indeed flipped direction. This revelation reshapes our understanding of how magnetic fields function in black hole environments, which are believed to funnel material from the surrounding accretion disks into the black hole.

Although the specific cause of the magnetic field reversal remains unclear, scientists suggest that it may stem from a combination of internal dynamics associated with the black hole and external pressures from its environment.

Astrophysicist Jess McIver from the University of British Columbia, who did not participate in this study, expressed surprise at the observation of such a significant change within a relatively short timeframe. “This changes my thinking about the stability of supermassive black holes and their environments,” McIver stated, highlighting the implications of these findings on our comprehension of black hole physics.