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 Λ>425 and for the mass ratio of q<2.03 at 90\% confidence, with peaks in the likelihood near Λ=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.
@article{arxiv.1901.06052,
title = {Can a black hole-neutron star merger explain GW170817, AT2017gfo, GRB170817A?},
author = {Michael W. Coughlin and Tim Dietrich},
journal= {arXiv preprint arXiv:1901.06052},
year = {2019}
}