http://arxiv.org/abs/1710.05869
The leading theory for short-duration GRBs ($\lesssim$ 2s) is neutron star-neutron star (NS-NS) mergers or black hole-NS mergers, while bursts of soft gamma-ray repeaters (SGRs) in a nearby galaxy may mimic a short GRB. If a short GRB due to a merger occur in the local Universe (i.e., redshift $\le$ {0.1-0.2}), the merger event can simultaneously produce gravitational wave signal detectable by current detectors like advanced LIGO/Virgo, while no detectable signal is expected for an SGR. Recently, Fermi GBM detected a short GRB~170817A. It is reported to have a redshift of 0.0098. Assuming this is true, it will have two profound implications: (1) the isotropic-equivalent $\gamma$-ray energetics, E${iso,\gamma}$, of GRB~170817A is only about 4 $\times$ 10$^{46}$ erg, much lower than a typical cosmological short GRB whose E${iso,\gamma}$ is $\gtrsim10^{50}$erg. So it will be the first low-luminosity GRB of short duration. An interesting explanation is that it is an off-axis short GRB with structured jets; and (2) given its proximity, the GW signal of a merger should have been detected by advanced LIGO/Virgo.
X. He, P. Tam and R. Shen
Tue, 17 Oct 17
27/163
Comments: 7 pages, 4 figures