http://arxiv.org/abs/1710.05905
Gravitational waves from a merger of two neutron stars were discovered for the first time in GW170817, together with diverse electromagnetic (EM) counterparts. To make constraints on a relativistic jet from the NS merger, we calculate the EM signals in (1) the short gamma-ray burst sGRB 170817A from an off-axis jet, (2) the optical-infrared macronova (or kilonova), especially the blue macronova, from a jet-powered coccon, and (3) the X-ray and radio afterglows from the interaction between the jet and interstellar medium. We find that a typical sGRB jet is consistent with these observations, and there is a parameter space to explain all the observations in a unified fashion with an isotropic energy $\sim 10^{51}$–$10^{52}$ erg, opening angle $\sim 20^{\circ}$, and viewing angle $\sim 30^{\circ}$. The off-axis emission is less de-beamed than the point source case because the viewing angle is comparable to the opening angle. The ambient density might be low $\sim 10^{-3}$–$10^{-6}$ cm$^{-3}$, which can be tested by the future observations of radio flares and X-ray remnants.
K. Ioka and T. Nakamura
Tue, 17 Oct 17
135/163
Comments: 22 pages, 6 figures
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