Did a phenomenon comparable to a volcanic eruption occur in a magnetar?

SGR 1935+2154, located about 30,000 light-years distant from Earth, is a magnetar, a highly magnetic class of neutron star (a star corpse less dense than a black hole). On October 5, 2020, the rotation speed of SGR 1935+2154 suddenly slowed down. A few days later, it began to emit radio waves. Thanks to the timely measurements made from specialized orbital telescopes, the team led by astrophysicist Matthew Baring, from Rice University in the United States, was able to verify a new theory about a possible cause of this rare sudden reduction in the rotation speed of the star.

Analyzes carried out indicate that the sudden slowdown could have been caused by a volcanic-like rupture on the star’s surface that spewed a “wind” of massive particles into space. The investigation allowed us to deduce how such a wind could alter the magnetic fields of the star, seeding the conditions that were probably what made possible the radio emissions that were later captured by the large Chinese FAST radio telescope.

“The possibility that neutron stars have something equivalent to volcanoes on their surface has been considered,” says Baring. “Our findings suggest that this is the case, and that this time the ‘volcano eruption’ most likely occurred at or near one of the star’s two magnetic poles.”

SGR 1935+2154 and other magnetars belong to the general category of neutron stars. A neutron star is the compact core of a dead star. Twenty kilometers in diameter and as dense as the nucleus of an atom, magnetars rotate once every few seconds and have the strongest magnetic fields in the universe. In addition, they emit intense radiation, including X-rays and occasionally radio waves and gamma rays. Astronomers can decipher many features of these stars from these emissions.

The study is titled “Magnetar spin-down glitch clearing the way for FRB-like bursts and a pulsed radio episode”. And it has been published in the academic journal Nature Astronomy.