Identification of a Local Sample of Gamma-Ray Bursts Consistent with a Magnetar Giant Flare Origin

Burns, E. and Svinkin, D. and Hurley, K. and Wadiasingh, Z. and Negro, M. and Younes, G. and Hamburg, R. and Ridnaia, A. and Cook, D. and Cenko, S. B. and Aloisi, R. and Ashton, G. and Baring, M. and Briggs, M. S. and Christensen, N. and Frederiks, D. and Goldstein, A. and Hui, C. M. and Kaplan, D. L. and Kasliwal, M. M. and Kocevski, D. and Roberts, O. J. and Savchenko, V. and Tohuvavohu, A. and Veres, P. and Wilson-Hodge, C. A. (2021) Identification of a Local Sample of Gamma-Ray Bursts Consistent with a Magnetar Giant Flare Origin. The Astrophysical Journal Letters, 907 (2). L28. ISSN 2041-8205

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Abstract

Cosmological gamma-ray bursts (GRBs) are known to arise from distinct progenitor channels: short GRBs mostly from neutron star mergers and long GRBs from a rare type of core-collapse supernova (CCSN) called collapsars. Highly magnetized neutron stars called magnetars also generate energetic, short-duration gamma-ray transients called magnetar giant flares (MGFs). Three have been observed from the Milky Way and its satellite galaxies, and they have long been suspected to constitute a third class of extragalactic GRBs. We report the unambiguous identification of a distinct population of four local (<5 Mpc) short GRBs, adding GRB 070222 to previously discussed events. While identified solely based on alignment with 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 nondetection in gravitational waves all point to an extragalactic MGF origin. Despite the small sample, the inferred volumetric rates for events above 4 × 1044 erg of ${R}_{\mathrm{MGF}}={3.8}_{-3.1}^{+4.0}\times {10}^{5}$ Gpc−3 yr−1 make MGFs 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 CCSN as key progenitors of magnetars.

Item Type: Article
Subjects: Oalibrary Press > Physics and Astronomy
Depositing User: Managing Editor
Date Deposited: 18 May 2023 05:01
Last Modified: 06 Feb 2024 04:17
URI: http://asian.go4publish.com/id/eprint/2076

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