Madrid, Dec 22 (EFE) .- GRBs, or gamma ray bursts, are the most violent explosions in the Universe since the Big Bang, capable of releasing in a few seconds an amount of energy comparable to that emitted by the Sun in all its life.
Some GRBs are originated by magnetars, neutron stars powered by the most intense magnetic fields in the universe that can contain half a million times the mass of the Earth in a diameter of 20 kilometers. Only about thirty are known.
A team of scientists headed by the Andalusian Institute of Astrophysics (IAA-CSIC) has studied one of these eruptions in detail and has managed to measure the oscillations, or pulses, in its brightness during the instants of greatest energy.
This information, published today in the journal Nature, is crucial to understanding the still enigmatic giant flares of magnetars.
“Even in an inactive state, magnetars can be one hundred thousand times more luminous than our Sun”, points out Alberto J. Castro-Tirado, a researcher at the IAA and the University of Malaga, who is leading the work.
In the case of the flare studied, GRB200415, which occurred on April 15, 2020 and lasted around one tenth of a second, the energy released is equivalent to that which our Sun would radiate in one hundred thousand years.
“The observations revealed multiple pulses, with a first pulse appearing only about tens of microseconds, much faster than other extreme transients,” says Castro-Tirado.
It is believed that the eruptions in magnetars may be due to instabilities in their magnetosphere or to a kind of earthquakes produced in their crust, a rigid and elastic layer about a kilometer thick.
“Regardless of the trigger, a type of waves will be created in the star’s magnetosphere, Alfvén waves, which are well known in the Sun and which, while bouncing back and forth, interact with each other, dissipating energy”, explains the investigator.