Fermi-GBM Observations of the SGR J1935+2154 Burst Forest
| Autor: | Kaneko, Yuki, Gogus, Ersin, Baring, Matthew G., Kouveliotou, Chryssa, Lin, Lin, Roberts, Oliver J., van der Horst, Alexander J., Younes, George, Keskin, Ozge, Coban, Omer Faruk |
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| Rok vydání: | 2021 |
| Předmět: | |
| Zdroj: | ApJL 916 (2021) L7 |
| Druh dokumentu: | Working Paper |
| DOI: | 10.3847/2041-8213/ac0fe7 |
| Popis: | 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 $\nu F_{\nu}$ spectral hardness (represented by $E_{\rm peak}$ 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. Comment: 23 pages, 8 figures, 1 table (machine-readable table provided separately), Matches the published version |
| Databáze: | arXiv |
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