http://arxiv.org/abs/1711.00243
In light of recent discovery of a faint short gamma-ray burst sGRB 170817A followed by the gravitational waves (GWs) from a merger of two neutron stars (NSs) GW170817, we investigate off-axis appearance of an sGRB prompt emission scattered by a cocoon, which is produced through the jet-merger-ejecta interaction, with either sub-relativistic or mildly-relativistic velocities. We show that the observed properties of GRB 170817A can be consistently explained by the Thomson-scattered emission with a typical sGRB jet, together by its canonical off-axis emission, supporting that an NS-NS merger is the origin of sGRBs. The scattering occurs at $\lesssim 10^{10}$–$10^{12}\,{\rm cm}$ not far from the central engine, implying the photospheric or internal shock origin of the sGRB prompt emission. The scattering model predicts a distribution of the spectral peak energy that is similar to the observed one but with a cutoff around $\sim$ MeV energy, and its correlations with the luminosity, duration, and time lag from GWs, providing a way to distinguish it from alternative models.
S. Kisaka, K. Ioka, K. Kashiyama, et. al.
Thu, 2 Nov 17
38/71
Comments: 8 pages, 2 figures
You must be logged in to post a comment.