We've just taken another step toward comprehending enormous magnetar explosions.
For the first time, a group of international researchers was able to measure oscillations in the brightness of a magnetar during its most violent moments.
This was a brutal moment in time indeed, as in less than a tenth of a second, the magnetar expelled energy equivalent to that created by the sun in 100,000 years!
Why you should know about magnetars (and why they're scary)
A magnetar is a rare form of neutron star distinguished by an extremely powerful magnetic field. Its field is about 1,000 times stronger than that of a regular neutron star — a trillion times greater than that of the Earth! We only know about 30 of these objects, since detecting them is a difficult task for our current technologies. While they are known to suffer violent eruptions, we know relatively little due to their unexpected nature and their short duration time of barely tenths of a second.
For the past two decades, scientists have been wondering whether magnetars have high-frequency oscillations. In the latest study, which was conducted by six researchers from the University of Valencia and Spanish collaborators and published in the journal Nature, an observation of a magnetar's brightness during one of its most violent times was carried out without the need for human intervention, thanks to an artificial intelligence system built at the Image Processing Laboratory (IPL) of the University of Valencia (UV).
"The explosion of the magnetar, which lasted approximately a 10th of a second, was discovered on April 15, 2020, in the midst of the pandemic," explained co-author Víctor Reglero, professor of Astronomy and Astrophysics at the UV, in a press release. The eruption was detected by the Atmosphere Space Interactions Monitor (ASIM) instrument, which is currently on the International Space Station (ISS), and Reglero is one of its architects. "Since then we have developed very intense data analysis work, since it was a 10 ** 16 Gauss neutron star and located in another galaxy. A true cosmic monster," he added.
The oscillations recorded in the eruption were found to be consistent with the emission produced by the interplay of Alfvén waves, the energy of which is rapidly absorbed by the crust. The magnetic reconnection process and the pulses identified in GRB2001415 finished in a few milliseconds, fading 3.5 milliseconds after the main burst.
This analysis has allowed researchers to estimate that the volume of the eruption was comparable to, if not bigger than, the volume of the neutron star itself.
"Even in an inactive state, magnetars can be 100,000 times more luminous than our sun, but in the case of the flash that we have studied—GRB2001415—the energy that was released is equivalent to that which our sun radiates in 100,000 years," explained lead researcher Alberto J. Castro-Tirado, from the IAA-CSIC.
We're still not sure what makes magnetars so scarily magnetic, but this discovery adds to our understanding of magnetars, and ongoing observations in nearby galaxies will aid in our comprehension of this phenomenon, as will a better understanding of fast radio bursts, which are currently one of astronomy's most puzzling occurrences.