Using sensitive instruments onboard ESA’s International Gamma-Ray Astrophysics Laboratory (Integral) mission, astronomers have detected a gamma-ray burst named GRB 231115A from the center of Messier 82 (M82, NGC 3034 or the Cigar Galaxy), a starburst irregular galaxy located 12 million light-years away in the constellation of Ursa Major. They suggest that GRB 231115A’s spectral and timing properties, together with X-ray and optical observations a few hours after the event and the lack of a gravitational wave signal, indicate that this burst was the result of a giant flare from a magnetar. They conclude that starburst galaxies such as Messier 82, known to produce magnetars, may be promising targets for studying giant flares.
Giant flares are short explosive events releasing extremely large amounts of energy as gamma-ray bursts (GRBs).
Only three such flares have been seen from magnetars in our Milky Way Galaxy and the nearby Large Magellanic Cloud in around 50 years.
Observations of giant flares from magnetars further afield are impeded by the fact that the source of energetic bursts can be difficult to determine at long distances.
“Some young neutron stars have extra strong magnetic fields, more than 10,000 times that of typical neutron stars. These are called magnetars. They emit energy away in flares, and occasionally these flares are gigantic,” said Dr. Ashley Chrimes, an astronomer at ESA.
“However, in the past 50 years of gamma-ray observations, only three giant flares have been seen from magnetars in our Galaxy.”
“These outbursts are very strong: one that was detected in December 2004, came from 30,000 light-years from us but was still powerful enough to affect the upper layers of Earth’s atmosphere. Similar to how solar flares, coming from much closer to us, influence it. “
“The flare detected by Integral is the first confirmation of a magnetar outside of the Milky Way,” said Dr. Sandro Mereghetti, an astronomer at the National…
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