http://arxiv.org/abs/1905.00314
For binary neutron star (BNS) mergers detectable from the nearby Universe, the distribution of orbital inclination angles ($\iota$), as measured from gravitational wave (GW) observations follows Schutz distribution \citep{Schutz2011}. If the BNSs produce short GRBs which are independently detected, they can trigger BNS detections and then the resulting inclination angle distribution would also depend on the jet structure of the SGRBs and hence deviate from the Schutz distribution. We demonstrate this by obtaining the inclination angle distribution by assuming all the BNS mergers to have SGRB counterparts with structured jets of Gaussian-like profiles, with the half opening angle of the jet core $\theta_c=5^\circ$ and the total $\gamma-$ray energy in the rest frame $E_{\gamma}=10^{50}$ erg, consistent with what was inferred for GRB170817A. With the new distribution, we find that the detection probability of low inclination angle events significantly increases depending on the GW network configuration/sensitivity. Assuming a 50\% duty cycle for GW detectors and a 60\% sky coverage for Fermi GBM, we find that almost 52\% of the total BNS detections in O3 with LHV network will have coincident prompt $\gamma$-ray detections. With the five-detector network LHVKI with designed sensitivity and with Aplus sensitivity, the total BNS detections increases, however, the coincident detection fraction decreases as 28\% and as 19\%.
M. Saleem
Thu, 2 May 19
5/45
Comments: 6 pages, 1 figure
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