A bright γ-ray flare interpreted as a giant magnetar flare in NGC 253
Journal
Date Issued
2021
Author(s)
Svinkin, D.
•
Frederiks, D.
•
Hurley, K.
•
Aptekar, R.
•
Golenetskii, S.
•
Lysenko, A.
•
Ridnaia, A. V.
•
Tsvetkova, A.
•
Ulanov, M.
•
Cline, T. L.
•
Mitrofanov, I.
•
Golovin, D.
•
Kozyrev, A.
•
Litvak, M.
•
Sanin, A.
•
Goldstein, A.
•
Briggs, M. S.
•
Wilson-Hodge, C.
•
von Kienlin, A.
•
Zhang, X. -L.
•
Rau, A.
•
Savchenko, V.
•
Bozzo, E.
•
Ferrigno, C.
•
Ubertini, P.
•
•
•
Barthelmy, S.
•
Cummings, J.
•
Krimm, H.
•
Palmer, D. M.
•
Boynton, W.
•
Fellows, C. W.
•
Harshman, K. P.
•
Enos, H.
•
Starr, R.
Abstract
Soft γ-ray repeaters exhibit bursting emission in hard X-rays and soft γ-rays. During the active phase, they emit random short (milliseconds to several seconds long), hard-X-ray bursts, with peak luminosities[1] of 10^36 to 10^43 erg per second. Occasionally, a giant flare with an energy of around 10^44 to 10^46 erg is emitted2. These phenomena are thought to arise from neutron stars with extremely high magnetic fields (10^14 to 10^15 gauss), called magnetars[1,3,4]. A portion of the second-long initial pulse of a giant flare in some respects mimics short γ-ray bursts[5,6], which have recently been identified as resulting from the merger of two neutron stars accompanied by gravitational-wave emission[7]. Two γ-ray bursts, GRB 051103 and GRB 070201, have been associated with giant flares[2,8,9,10,11]. Here we report observations of the γ-ray burst GRB 200415A, which we localized to a 20-square-arcmin region of the starburst galaxy NGC 253, located about 3.5 million parsecs away. The burst had a sharp, millisecond-scale hard spectrum in the initial pulse, which was followed by steady fading and softening over 0.2 seconds. The energy released (roughly 1.3 × 10^46 erg) is similar to that of the superflare[5,12,13] from the Galactic soft γ-ray repeater SGR 1806−20 (roughly 2.3 × 10^46 erg). We argue that GRB 200415A is a giant flare from a magnetar in NGC 253.
Volume
589
Issue
7841
Start page
211
Issn Identifier
0028-0836
Ads BibCode
2021Natur.589..211S
Rights
open.access
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