Astronomers have revealed how magnetar outbreaks occur and why they fly to Earth

A short burst of high-energy light swept across the solar system on April 15, triggering many space instruments, including those aboard NASA and European missions. Now several international scientific groups have come to the conclusion that the explosion originated from a supermagnetic remnant of a magnetar located in a nearby galaxy.

The discovery confirms long-standing suspicions that some of the gamma-ray bursts are cosmic eruptions found in the sky almost daily, in fact, are powerful flares from magnetars located relatively close to home.

“The discovery of the existence of a population of extragalactic magnetic flares provides LIGO and nuclear physicists with an opportunity to explore key questions in the universe in the future.”

Eric Burns, Associate Professor of Physics and Astronomy.

Magnetic flare on April 15 proves that these events constitute a separate class of GRBs. Burns directed the investigation of additional suspects using data from multiple missions. Flares near the M81 galaxy in 2005 and the Andromeda galaxy, or M31, in 2007 were already considered giant flares, and the team identified the flare in M83 in 2007. Scientists have also observed giant flares in 1979, 1998 and 2004.

“This is a small sample, but we now have a better idea of ​​their true energies and how far away we can detect them. A few percent of short GRBs can actually be giant magnetars. In fact, they may be the most common high-energy bursts we’ve found so far outside our galaxy – about five times more likely than supernovae. ”

Eric Burns, Associate Professor of Physics and Astronomy.

GRBs are the most powerful explosions in space to be detected billions of light years away. Those that last less than two seconds are called short gamma-ray bursts, and they occur when a pair of spinning neutron stars, which are crushed remnants of exploding stars, spiral into each other and merge. Astronomers have confirmed this scenario for at least some short bursts of gamma-ray bursts in 2017, when the burst followed the arrival of gravitational waves or ripples in spacetime created by merging neutron stars 130 million light years away.

“The favorite explanation for most short gamma-ray bursts is that they emit a jet of debris moving at a speed close to the speed of light, resulting from the merger of neutron stars or a neutron star and a black hole. LIGO discovered that there was a merging of compact objects and a short gamma flash. Together, we know that what we observed was a merger of two neutron stars, which strongly confirms the relationship. ”

Eric Burns of the GRB Monitoring Team, NASA Goddard Space Flight Center.
Magnetars are neutron stars with the strongest known magnetic fields, a thousand times the intensity of typical neutron stars. Small perturbations in the magnetic field can cause magnetars to erupt in sporadic bursts of X-rays for weeks or longer. Magnetars rarely cause huge eruptions called giant flares that produce gamma rays, the highest energy form of light.

At about 4:42 am on April 15, 2020, a short, powerful burst of X-rays and gamma rays passed Mars, triggering a Russian high-energy neutron detector aboard NASA’s Mars Odyssey spacecraft, which has been orbiting the planet since 2001. About 6.6 minutes later, the explosion triggered the Russian Konus instrument aboard NASA’s Wind satellite, which revolves around a point between the Earth and the Sun, located at a distance of about 1.5 million km. After another 4.5 seconds, the radiation passed through the Earth, launching instruments on NASA’s Fermi gamma-ray telescope, as well as on the INTEGRAL satellite and the European Space Agency’s atmospheric-space interaction monitor aboard the ISS. The pulse of radiation lasted only 140 milliseconds, that is, with the speed of blinking or clicking a finger.

Giant flares from magnetars in the Milky Way and its satellites evolve in their own way, with a rapid rise to maximum brightness, followed by a more gradual tail of fluctuating radiation. These changes are due to the rotation of the magnetar, which repeatedly moves the flare to the Earth and uses it as a beacon.

Observing this wobbling tail is compelling evidence of a giant flare. However, when viewed from a distance of millions of light years, this radiation is too dim to detect with modern instruments. Since these signatures are absent, giant flares in the vicinity of the Galaxy can be disguised as much more distant and powerful merger-type gamma-ray bursts.

Author: John Kessler
Graduated From the Massachusetts Institute of Technology. Previously, worked in various little-known media. Currently is an editor and developer of Free News.
Function: Director