Multimessenger Parameter Estimation of GW170817

Abstract

We combine gravitational wave (GW) and electromagnetic (EM) data to perform a Bayesian parameter estimation of the binary neutron star (NS) merger GW170817. The EM likelihood is constructed from a fit to a large number of numerical relativity simulations which we combine with a lower bound on the mass of the remnant's accretion disk inferred from the modeling of the EM light curve. In comparison with previous works, our analysis yields a more precise determination of the tidal deformability of the binary, for which the EM data provide a lower bound, and of the mass ratio of the binary, with the EM data favoring a smaller mass asymmetry. The 90\% credible interval for the areal radius of a $1.4M_{\odot }$ NS is found to be $12.2_{-0.8}^{+1.0}\pm 0.2\mathrm{km}$ (statistical and systematic uncertainties).

Comments: 7 pages, 3 figures, accepted to the EPJA Topical Issue: The first Neutron Star Merger Observation - Implications for Nuclear Physics