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Magnetar Giant Flares

Presentation #302.03 in the session New Insights into Magnetars, the Most Magnetic Stars in the Cosmos.

Published onMay 03, 2024
Magnetar Giant Flares

Magnetars are slowly-rotating neutron stars with extremely strong magnetic fields (1013-15 G), episodically emitting 100 ms long X-ray bursts with energies of ~1040-41 erg. Rarely, they produce extremely bright, energetic giant flares that begin with a short (200 ms) intense flash, followed by fainter emission lasting several minutes that is modulated by the magnetar spin period (typically 2-12 s), thus confirming their origin. Over the last 40 years, only three such flares have been observed within our local galactic group, which all suffered from instrumental saturation due to their extreme intensity. Several extragalactic giant flare candidates have been detected over the same period, and have been proposed to constitute a subset of short gamma-ray bursts. Their initial bright flash is readily observable out to distances of < 60 Mpc, but the sensitivity of current instrumentation prevents us from detecting the pulsating tail to distances slightly beyond the Magellanic clouds. In this talk, we evaluate the spectral and temporal behavior of the initial flash of several recently reported extragalactic giant flares (i.e., GRB 200415A, GRB 180128A and more recently, GRB 231115A), using X- and gamma-ray data. Such observations are providing tantalizing clues as to the nature of these sources. The implications of this work for future studies of these high-energy studies, will also be provided.

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