Breschi, MatteoMatteoBreschiPerego, AlbinoAlbinoPeregoBernuzzi, SebastianoSebastianoBernuzziDEL POZZO, WALTERWALTERDEL POZZONedora, VsevolodVsevolodNedoraRadice, DavidDavidRadiceVESCOVI, DiegoDiegoVESCOVI2025-02-142025-02-1420210035-8711http://hdl.handle.net/20.500.12386/35967The 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 (NS) merger observed on 2017 August 17, is a milestone in multimessenger astronomy and provides new constraints on the NS equation of state. We perform Bayesian inference and model selection on AT2017gfo using semi-analytical, multicomponents models that also account for non-spherical ejecta. Observational data favour anisotropic geometries to spherically symmetric profiles, with a log-Bayes' factor of ~10<SUP>4</SUP>, and favour multicomponent 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 $120\lt \tilde{\Lambda }\lt 1110$. Finally, we combine the predictions from AT2017gfo with those from GW170817, constraining the radius of a NS of 1.4 M<SUB>⊙</SUB> to 12.2 ± 0.5 km (1σ level). This prediction could be further strengthened by improving kilonova models with numerical-relativity information.STAMPAenArticle10.1093/mnras/stab12872-s2.0-85128520405http://arxiv.org/abs/2101.01201v3https://academic.oup.com/mnras/article/505/2/1661/62747002021MNRAS.505.1661BFIS/05 - ASTRONOMIA E ASTROFISICA