The discovery of the compact binary coalescence in both gravitational waves and electromagnetic radiation marks a breakthrough in the field of multi-messenger astronomy and has improved our knowledge in a number of research areas .
However , an open question is the exact origin of the observables and if one can confirm reliably that GW170817 and its electromagnetic counterparts resulted from a binary neutron star merger .
To answer the question if the observation of GW170817 , GRB170817A , and AT2017gfo could be explained by the merger of a neutron star with a black hole , we perform a joint multi-messenger analysis of the gravitational waves , the short gamma-ray burst , and the kilonova .
Assuming a black-hole neutron star system , we derive multi-messenger constraints for the tidal deformability of the NS of \Lambda > 425 and for the mass ratio of q < 2.03 at 90 % confidence , with peaks in the likelihood near \Lambda = 830 and q = 1.0 .
Overall , we find that a black hole-neutron star merger could explain the observed signatures , however , our analysis shows that a binary neutron star origin of GW170817 seems more plausible .