Can a black hole-neutron star merger explain GW170817, AT2017gfo, GRB170817A?

• Published in: arXiv.org
• Main Authors: Coughlin, Michael W, Dietrich, Tim
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 14.11.2019
• Subjects: Astronomy; Binary stars; Black holes; Coalescing; Deformation mechanisms; Electromagnetic radiation; Formability; Gamma rays; Gravitation; Gravitational waves; Neutron stars; Neutrons; Physics - General Relativity and Quantum Cosmology; Physics - High Energy Astrophysical Phenomena; Signatures; Star mergers
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1901.06052

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.