Detection of the third class of gamma-ray bursts: magnetar giant flares.

Discussion timeslot (ZOOM-Meeting): 14. July 2021 - 18:00
ZOOM-Meeting URL: https://desy.zoom.us/j/98542982538
ZOOM-Meeting ID: 98542982538
ZOOM-Meeting Passcode: ICRC2021
Corresponding Session: https://icrc2021-venue.desy.de/channel/47-The-central-engines-of-fast-transients-Gamma-Ray-Bursts-and-Fast-Radio-Bursts-GAD-GAI-MM/112
Live-Stream URL: https://icrc2021-venue.desy.de/livestream/Discussion-04/5

Abstract:
'Around 11.4 million years ago a young, highly magnetized neutron star, a magnetar, in the Sculptor galaxy released an enormous amount of energy in the form of a giant flare. On April 15$^{rm th}$ 2020 some of the emitted photons were detected by a number of gamma-ray telescopes around Earth and Mars. While the analysis of this event, GRB 200415A, was interesting in its own right, it resulted in broader implications for both magnetar and gamma-ray burst (GRB) science.rnThe resulting population study of magnetar giant flares (MGFs), led to the unambiguous identification of a distinct population of 4 local ( smaller 5 Mpc) short GRBs. While identified solely based on alignment to nearby star-forming galaxies, their rise time and isotropic energy release are independently inconsistent with the larger short GRB population at larger 99.9% confidence. These properties, the host galaxies, and non-detection in gravitational waves all point to an extragalactic MGF origin. The inferred volumetric rates for events above $4 times 10^{44}$erg of $R = 3.8^{+4.0}_{-3.1} times 10^5$Gpc$^{−3}$yr$^{−1}$ place MGFs as the dominant gamma-ray transient detected from extragalactic sources. As previously suggested, these rates imply that some magnetars produce multiple MGFs, providing a source of repeating GRBs. The rates and host galaxies favor common core-collapse supernova as key progenitors of magnetars.'

Authors: Michela Negro | Burns Eric | Svinkin Dimitry | Hurley Kevin | Zorawar Wadiasingh | Younes Georges | Hamburg Rachel | Cook David
Indico-ID: 792
Proceeding URL: https://pos.sissa.it/395/630