LIGO-Virgo and Fermi collaborations recently reported a possible joint detection of a sub-threshold gravitational wave ( GW ) event and a sub-threshold gamma-ray burst ( GRB ) , GBM-190816 , that occurred 1.57 s after the merger .
Since it takes long for the official LIGO-Virgo/Fermi Collaboration ’ s results to be released , we decide to independently process the publicly available data and investigate the physical implications of this potential association .
We perform a detailed analysis of the observational properties of the GBM-190816 using Fermi /GBM data .
By studying its signal-to-noise ratio , duration , f -parameter , spectral properties , energetic properties , and its compliance with some GRB statistical correlations , we confirm that this event is likely a typical short GRB with a luminosity of 1.02 _ { -0.80 } ^ { +2.84 } \times 10 ^ { 49 } erg s ^ { -1 } .
Based on the available information of the sub-threshold GW event , we infer the mass ratio , q , of the binary compact stars in the range of \sim [ 2.142 , 5.795 ] .
The leading physical scenario invokes an NS-BH merger system with the NS tidally disrupted .
We derive the physical properties of such a system ( including mass ratio q , the spin parameters , and the observer ’ s viewing angle ) that are required to produce a GRB within the framework of such a scenario .
The GW data in principle allow NS-BH systems with no tidal disruption ( the plunge events ) or BH-BH mergers .
The generation of a GRB in these systems requires that at least one of the merger member is charged .
We apply the charged compact binary coalescence ( cCBC ) theory to derive the model parameters to account for GBM-190816 .
The cases for both constant and increasing charges in the merging members are discussed .
Finally , since in NS-BH or BH-BH merger systems a BH exists immediately after the merger so that there is no waiting time before launching a jet , the fact that the observed delay time scale is comparable to that of the NS-NS merger event GW170817/GRB 170817A suggests that the commonly observed GW-GRB time delay is mainly defined by the time scale for the jet propagates to the energy dissipation / GRB emission site .