Multimessenger Bayesian parameter inference of a binary neutron star merger

ABSTRACT The combined detection of a binary neutron star merger in both gravitational waves (GWs) and electromagnetic (EM) radiation spanning the entire spectrum – GW170817/AT2017gfo/GRB170817A – marks a breakthrough in the field of multimessenger astronomy. Between the plethora of modelling and observations, the rich synergy that exists among the available data sets creates a unique opportunity to constrain the binary parameters, the equation of state of supranuclear density matter, and the physical processes at work during the kilonova and gamma-ray burst. We report, for the first time, Bayesian parameter estimation combining information from GW170817, AT2017gfo, and GRB170817 to obtain truly multimessenger constraints on the tidal deformability 302, 860, total binary mass M ∈ 2. 722, 2. 751 M⊙, the radius of a 1. 4 solar mass neutron star R 11. 3, 13. 5 \, \, km (with additional 0. 2\ km systematic uncertainty), and an upper bound on the mass ratio of q ≤ 1. 27, all at 90 per cent confidence. Our joint novel analysis uses new phenomenological descriptions of the dynamical ejecta, debris disc mass, and remnant black hole properties, all derived from a large suite of numerical relativity simulations.