摘要
Jet precession has previously been proposed to explain the apparently repeating features in the light curves of a few gamma-ray bursts(GRBs).In this paper,we further apply the precession model to a bright GRB 220408B by examining both its temporal and spectral consistency with the predictions of the model.As one of the recently confirmed GRBs observed by our GRID CubeSat mission,GRB 220408B is noteworthy as it exhibits three apparently similar emission episodes.Furthermore,the similarities are reinforced by their strong temporal correlations and similar features in terms of spectral evolution and spectral lags.Our analysis demonstrates that these features can be well explained by the modulated emission of a Fast-Rise-Exponential-Decay(FRED)shape light curve intrinsically produced by a precessing jet with a precession period of 18.4_(-0.2)~(+0.2)s,a nutation period of11.1_(-0.2)~(+0.2)s and viewed off-axis.This study provides a straightforward explanation for the complex yet similar multiepisode GRB light curves.
基金
support by the National Key Research and Development Programs of China(2022YFF0711404,2022SKA0130102)
the National SKA Program of China(2022SKA0130100)
the National Natural Science Foundation of China(grant Nos.11833003,U2038105,U1831135,12121003)
the science research grants from the China Manned Space Project with NO.CMS-CSST-2021-B11
the Fundamental Research Funds for the Central Universities
the Program for Innovative Talents and Entrepreneur in Jiangsu
supported by the National Postdoctoral Program for Innovative Talents(grant No.BX20200164)。
