Fermi/GBM observations of the SGRJ1935+2154 burst forest

Kaneko, Yuki and Göğüş, Ersin and Baring, Matthew G. and Kouveliotou, Chryssa and Lin, Lin and Roberts, Oliver J. and Van Der Horst, Alexander J. and Younes, George and Keskin, Özge and Çoban, Ömer Faruk (2021) Fermi/GBM observations of the SGRJ1935+2154 burst forest. Astrophysical Journal Letters, 916 (1). ISSN 2041-8205 (Print) 2041-8213 (Online)

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During 2020 April and May, SGR J1935+2154 emitted hundreds of short bursts and became one of the most prolific transient magnetars. At the onset of the active bursting period, a 130 s burst "forest,"which included some bursts with peculiar time profiles, were observed with the Fermi/Gamma-ray Burst Monitor (GBM). In this Letter, we present the results of time-resolved spectral analysis of this burst "forest"episode, which occurred on 2020 April 27. We identify thermal spectral components prevalent during the entire 130 s episode; high-energy maxima appear during the photon flux peaks, which are modulated by the spin period of the source. Moreover, the evolution of the ν F ν spectral hardness (represented by E peak or blackbody temperature) within the lightcurve peaks is anti-correlated with the pulse phases extrapolated from the pulsation observed within the persistent soft X-ray emission of the source six hours later. Throughout the episode, the emitting area of the high-energy (hotter) component is 1-2 orders of magnitude smaller than that for the low-energy component. We interpret this with a geometrical viewing angle scenario, inferring that the high-energy component likely originates from a low-altitude hotspot located within closed toroidal magnetic field lines.
Item Type: Article
Uncontrolled Keywords: machine-readable table
Divisions: Faculty of Engineering and Natural Sciences
Depositing User: Yuki Kaneko
Date Deposited: 30 Aug 2022 12:45
Last Modified: 30 Aug 2022 12:45
URI: https://research.sabanciuniv.edu/id/eprint/43707

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