Jul 12 – 23, 2021
Europe/Berlin timezone

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

Jul 14, 2021, 6:00 PM
1h 30m


Talk GAD | Gamma Ray Direct Discussion


Michela Negro (CRESST-GSFC)


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.
The resulting population study of magnetar giant flares (MGFs), led to the unambiguous identification of a distinct population of 4 local (<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 >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.


GRB, magnetar; giant flares;

Subcategory Experimental Results

Primary authors

Michela Negro (CRESST-GSFC) Dr Burns Eric (Louisiana State University) Dr Svinkin Dimitry (Ioffe Physical-Technical Institute) Dr Hurley Kevin (Space Sciences Laboratory, University of California) Dr Zorawar Wadiasingh (NASA GSFC) Dr Younes Georges (Department of Physics, The George Washington University) Ms Hamburg Rachel (Department of Space Science, University of Alabama in Huntsville) Dr Cook David (IPAC/Caltech)

Presentation materials