The gigantic eruption of a neutron star is "A true cosmic monster!"

Among the neutron stars, objects that can contain half a million times the mass of the Earth in a diameter of about twenty kilometers, a small group with the most intense magnetic field known stands out: the magnetars. These objects, of which only thirty are known, undergo violent eruptions still little known due to their unexpected nature and their duration of just tenths of a second. Detecting them is a challenge for science and technology.

An international scientific team has recently published in the journal Nature the study of the eruption of a magnetar in detail, managing to measure the oscillations - pulses - in the brightness of the magnetar during its most violent moments. These episodes are a crucial component in understanding giant magnetar eruptions. It is a question long debated in the last 20 years that today has an answer, if there are high frequency oscillations in the magnetars.

The work has the contribution of six researchers from the University of Valencia and a high participation Spanish - 15 scientists out of a total of 41. "Even in an inactive state, magnetars can be a hundred thousand times brighter than our Sun, but in the case of the flash we studied - the GRB2001415 - the energy that was released is equivalent to what our Sun radiates in a hundred thousand years ", underlines the researcher Alberto J. Castro-Tirado, of the IAA-CSIC.

The scientific community thinks that the eruptions in the magnetars may be due to instability in their magnetosphere or a sort of "earthquakes" produced in their crust, a rigid and elastic layer about one kilometer thick. “Regardless of the trigger, a type of wave is created in the star's magnetosphere - the Alfven - which are well known in the Sun and which interact with each other, dissipating energy,” explained Alberto J. Castro-Tirado.

According to the study now published in Nature, the oscillations detected in the eruption are consistent with the emission produced by the interaction between the Alfvén waves, whose energy is rapidly absorbed by the crust. Thus, in a few milliseconds the magnetic reconnection process ends and therefore also the pulses detected in GRB2001415, which disappeared 3.5 milliseconds after the main burst. The analysis of the phenomenon made it possible to estimate that the volume of the eruption was similar or even greater than that of the neutron star itself.

According to the authors of the article now published in Nature, this eruption provided a crucial component for understanding how magnetic stresses are produced in and around a neutron star. Continuous monitoring of magnetars in nearby galaxies will help to understand this phenomenon and will also pave the way for a better understanding of fast radio bursts, currently one of the most enigmatic phenomena in astronomy.