Mapping dynamical ejecta and disk masses from numerical relativity simulations of neutron star mergers

Vsevolod Nedora, Federico Schianchi, Sebastiano Bernuzzi, David Radice, Boris Daszuta, Andrea Endrizzi, Albino Perego, Aviral Prakash, Francesco Zappa.


We present fitting formulae for the dynamical ejecta properties and remnant disk masses from a large sample of numerical relativity simulations. The considered data include some of the latest simulations with microphysical nuclear equations of state (EOS) and neutrino transport as well as other results with polytropic EOS available in the literature. Our analysis indicates that the broad features of the dynamical ejecta and disk properties can be captured by fitting expressions, that depends on mass ratio and reduced tidal parameter. The comparative analysis of literature data shows that microphysics and neutrino absorption have a significant impact on the dynamical ejecta properties. Microphysical nuclear equations of state leads to average velocities smaller than polytropic EOS, while including neutrino absorption results in larger average ejecta masses and electron fractions. Hence, microphysics and neutrino transport are necessary to obtain quantitative models of the ejecta in terms of the binary parameters.