In our home galaxy, a single magnetar has been discovered that emits short radio bursts, the nature of which is still the subject of scientific debate. The relative proximity to us of the magnetar SGR 1935 + 2154 gives scientists hope of unraveling the secrets of these objects, and a step in this direction has already been taken.
Magnetar SGR 1935 + 2154, 30 thousand light years from Earth, first produced a radio burst recorded by our instruments in 2020. A repeat signal occurred in October 2022. NASA specialists managed to quickly respond to the second event and send two scientific instruments towards the source: NICER, located on the ISS, to study the internal composition of neutron stars, and the orbital NuSTAR for nuclear spectroscopy. The results of the observations surprised scientists so much that they became the subject of a serious scientific work, published in the journal Nature on February 14.
It should be noted that magnetars – neutron stars with a diameter of about 20 km, surrounded by strong magnetic fields, left after supernova explosions – rotate very, very quickly. The average rotation speed of the SGR 1935+2154 is just over 3 revolutions per second. The radio bursts they emit are accompanied by colossal bursts of energy, also observed in the X-ray and gamma-ray range. In a split second, energy is released that our Sun gives off for one year, and sometimes more.
Such energy emissions can change the rotation speed of a neutron star, and they do change it. What provokes these processes remains in the realm of hypotheses. For example, these could be large asteroids striking a neutron star in the direction of rotation and against it. Scientists also consider possible the phenomenon of starquakes, which cause oscillations of the surface of the star with subsequent switching of magnetic field lines.
The observation of a radio burst in October 2022 made it possible to suspect another reason for the occurrence of these phenomena. The rapid reaction to the event and its study simultaneously by two different instruments showed that the magnetar reduced its rotation speed 100 times faster than in the case of all previous observations. The reduction in speed occurred in just 9 hours, whereas previously it took weeks and even months. Something sped up the process, and it had to be something new.
In their work, scientists prove that a magnetar could eject matter into space similar to the process of volcanic activity. The superdense interior of a neutron star must exist in a state of superfluidity. Thanks to this, the “liquid” can splash inside the star and transmit to it an impulse that would be able to crack the crust and produce an eruption. The strong magnetic fields of the magnetar would give this eruption an additional impulse, and something like a jet stream would form, which could give the neutron star acceleration or deceleration in the shortest possible time.
According to the researchers, they have discovered something new in the behavior of magnetars and intend to study the issue more closely, which promises to finally unravel the mystery of the birth of short radio bursts by magnetars.
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