The growing observed evidence shows that the long-and short-duration gamma-ray bursts(GRBs) originate from massive star core-collapse and the merger of compact stars,respectively.GRB 201221 D is a short-duration GRB l...The growing observed evidence shows that the long-and short-duration gamma-ray bursts(GRBs) originate from massive star core-collapse and the merger of compact stars,respectively.GRB 201221 D is a short-duration GRB lasting~0.1 s without extended emission at high redshift z=1.046.By analyzing data observed with the Swift/BAT and Fermi/GBM,we find that a cutoff power-law model can adequately fit the spectrum with a soft E=113keV,and isotropic energy E=1.36× 10erg.In order to reveal the possible physical origin of GRB 201221 D,we adopted multi-wavelength criteria(e.g.,Amati relation,ε-parameter,amplitude parameter,local event rate density,luminosity function,and properties of the host galaxy),and find that most of the observations of GRB 201221 D favor a compact star merger origin.Moreover,we find that α is larger than 2+βin the prompt emission phase which suggests that the emission region is possibly undergoing acceleration during the prompt emission phase with a Poynting-flux-dominated jet.展开更多
It is expected that there should be a spectral cutoff at the high energy end of emission from a prompt gamma-ray burst （GRB）, due to, e.g. γγ absorption and/or a high energy cutoff in the electron distribution. We...It is expected that there should be a spectral cutoff at the high energy end of emission from a prompt gamma-ray burst （GRB）, due to, e.g. γγ absorption and/or a high energy cutoff in the electron distribution. We analyze the spectral data of Fermi- LAT detected GRBs 080916C and 090926A, aiming at locating the spectral cutoff. By assuming that the prompt GRB spectrum at the high energy end is a power law with an exponential cutoff, our analysis finds that the cutoff energy Ecutoff depends on the photon index/3 and the cutoff occurs at very high energy, Ecutoff = 161＋533 GeV in GRB 080916C and Ecutoff ≥ 100 GeV （forβ ≈-2.3） in GRB 090926A. Such high energy photons, if they exist, may disfavor the synchrotron origin and need alternative generation mechanisms.展开更多
基金supported by the National Natural Science Foundation of China (grant Nos. 11922301 and 12133003)the Guangxi Science Foundation (grant Nos. 2017GXNSFFA198008 and AD17129006)+6 种基金support by the Program of Bagui Young Scholars Program, and special funding for Guangxi distinguished professors (Bagui Yingcai & Bagui Xuezhe)support by the National Key Research and Development Programs of China (2018YFA0404204)the National Natural Science Foundation of China (grant Nos. 11833003 and U2038105)the Program for Innovative Talents, Entrepreneur in Jiangsusupport by the Strategic Priority Research Program of the Chinese Academy of Sciences (grant Nos. XDA15310300, XDA15052100 and XDB23040000)support by the National Natural Science Foundation of China (grant Nos. 12041306 and 12103089)the Natural Science Foundation of Jiangsu Province (grant No. BK20211000)。
文摘The growing observed evidence shows that the long-and short-duration gamma-ray bursts(GRBs) originate from massive star core-collapse and the merger of compact stars,respectively.GRB 201221 D is a short-duration GRB lasting~0.1 s without extended emission at high redshift z=1.046.By analyzing data observed with the Swift/BAT and Fermi/GBM,we find that a cutoff power-law model can adequately fit the spectrum with a soft E=113keV,and isotropic energy E=1.36× 10erg.In order to reveal the possible physical origin of GRB 201221 D,we adopted multi-wavelength criteria(e.g.,Amati relation,ε-parameter,amplitude parameter,local event rate density,luminosity function,and properties of the host galaxy),and find that most of the observations of GRB 201221 D favor a compact star merger origin.Moreover,we find that α is larger than 2+βin the prompt emission phase which suggests that the emission region is possibly undergoing acceleration during the prompt emission phase with a Poynting-flux-dominated jet.
基金supported by the Open Research Program of the Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences
文摘It is expected that there should be a spectral cutoff at the high energy end of emission from a prompt gamma-ray burst （GRB）, due to, e.g. γγ absorption and/or a high energy cutoff in the electron distribution. We analyze the spectral data of Fermi- LAT detected GRBs 080916C and 090926A, aiming at locating the spectral cutoff. By assuming that the prompt GRB spectrum at the high energy end is a power law with an exponential cutoff, our analysis finds that the cutoff energy Ecutoff depends on the photon index/3 and the cutoff occurs at very high energy, Ecutoff = 161＋533 GeV in GRB 080916C and Ecutoff ≥ 100 GeV （forβ ≈-2.3） in GRB 090926A. Such high energy photons, if they exist, may disfavor the synchrotron origin and need alternative generation mechanisms.
