2021/01/31 by Matteo Breschi, Albino Perego, Sebastiano Bernuzzi +4 · 1 citation
Physics and Astronomy · #astro-ph.HE
paper · pdf · doi:10.1093/mnras/stab1287
arxiv created 2021/05/04 · arxiv updated 2021/05/26
The joint detection of the gravitational wave GW170817, of the short γ-ray burst GRB170817A and of the kilonova AT2017gfo, generated by the the binary neutron star merger observed on August 17, 2017, is a milestone in multimessenger astronomy and provides new constraints on the neutron star equation of state. We perform Bayesian inference and model selection on AT2017gfo using semi-analytical, multi-components models that also account for non-spherical ejecta. Observational data favor anisotropic geometries to spherically symmetric profiles, with a log-Bayes' factor of ∼104, and favor multi-component models against single-component ones. The best fitting model is an anisotropic three-component composed of dynamical ejecta plus neutrino and viscous winds. Using the dynamical ejecta parameters inferred from the best-fitting model and numerical-relativity relations connecting the ejecta properties to the binary properties, we constrain the binary mass ratio to q<1.54 and the reduced tidal parameter to 120<Λ<1110. Finally, we combine the predictions from AT2017gfo with those from GW170817, constraining the radius of a neutron star of 1.4~\rm M_\odot to 12.2±0.5~\rm km (1σ level). This prediction could be further strengthened by improving kilonova models with numerical-relativity information.