Vol 22, No 7

Probing the Progenitor of High-z Short-duration GRB 201221D and its Possible Bulk Acceleration in Prompt Emission

Hao-Yu Yuan, Hou-Jun Lj, Ye Li, Bin-Bin Zhang, Hui Sun et al.


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 201221D 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 \(E_{\rm p} = 113_{-7}^{+9}\) keV, and isotropic energy \(E_{\rm \gamma, iso} = 1.36^{+0.17}_{-0.14}\times 10^{51}\) erg. In order to reveal the possible physical origin of GRB 201221D, 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 201221D favor a compact star merger origin. Moreover, we find that \(\hat{\alpha}\) is larger than \(2 + \hat{\beta}\) in 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.


(stars:) gamma-ray burst: individual (GRB 201221D) – stars: massive – acceleration of particles

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