TY - JOUR
T1 - A Luminous Precursor in the Extremely Bright GRB 230307A
AU - Dichiara, S.
AU - Tsang, D.
AU - Troja, E.
AU - Neill, D.
AU - Norris, J. P.
AU - Yang, Y. H.
N1 - Publisher Copyright:
© 2023. The Author(s). Published by the American Astronomical Society.
PY - 2023/9/1
Y1 - 2023/9/1
N2 - GRB 230307A is an extremely bright long-duration GRB with an observed gamma-ray fluence of ≳3 × 10−3 erg cm−2 (10-1000 keV), second only to GRB 221009A. Despite its long duration, it is possibly associated with a kilonova, thus resembling the case of GRB 211211A. In analogy with GRB 211211A, we distinguish three phases in the prompt gamma-ray emission of GRB 230307A: an initial short duration, spectrally soft emission; a main long duration, spectrally hard burst; and a temporally extended and spectrally soft tail. We interpret the initial soft pulse as a bright precursor to the main burst and compare its properties with models of precursors from compact binary mergers. We find that to explain the brightness of GRB 230307A, a magnetar-like (≳1015 G) magnetic field should be retained by the progenitor neutron star. Alternatively, in the postmerger scenario, the luminous precursor could point to the formation of a rapidly rotating massive neutron star.
AB - GRB 230307A is an extremely bright long-duration GRB with an observed gamma-ray fluence of ≳3 × 10−3 erg cm−2 (10-1000 keV), second only to GRB 221009A. Despite its long duration, it is possibly associated with a kilonova, thus resembling the case of GRB 211211A. In analogy with GRB 211211A, we distinguish three phases in the prompt gamma-ray emission of GRB 230307A: an initial short duration, spectrally soft emission; a main long duration, spectrally hard burst; and a temporally extended and spectrally soft tail. We interpret the initial soft pulse as a bright precursor to the main burst and compare its properties with models of precursors from compact binary mergers. We find that to explain the brightness of GRB 230307A, a magnetar-like (≳1015 G) magnetic field should be retained by the progenitor neutron star. Alternatively, in the postmerger scenario, the luminous precursor could point to the formation of a rapidly rotating massive neutron star.
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U2 - 10.3847/2041-8213/acf21d
DO - 10.3847/2041-8213/acf21d
M3 - Article
AN - SCOPUS:85171141655
SN - 2041-8205
VL - 954
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
IS - 1
M1 - L29
ER -