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General Relativity and Quantum Cosmology, gr-qc,
Abstract:
We present twelve new simulations of unequal mass neutron star mergers. The
simulations were preformed with the SpEC code, and utilize nuclear-theory based
equations of state and a two-moment gray neutrino transport scheme with an
improved energy estimate based on evolving the number density. We model the
neutron stars with the SFHo, LS220 and DD2 equations of state (EOS) and we
study the neutrino and matter emission of all twelve models to search for
robust trends between binary parameters and emission characteristics. We find
that the total mass of the dynamical ejecta exceeds $0.01M_\odot$ only for SFHo
with weak dependence on the mass-ratio across all models. We find that the
ejecta have a broad electron fraction ($Y_e$) distribution ($\approx
0.06-0.48$), with mean $0.2$. $Y_e$ increases with neutrino irradiation over
time, but decreases with increasing binary asymmetry. We also find that the
models have ejecta with a broad asymptotic velocity distribution ($\approx
0.05-0.7c$). The average velocity lies in the range $0.2c - 0.3c$ and decreases
with binary asymmetry. Furthermore, we find that disk mass increases with
binary asymmetry and stiffness of the EOS. The $Y_e$ of the disk increases with
softness of the EOS. The strongest neutrino emission occurs for the models with
soft EOS. For (anti) electron neutrinos we find no significant dependence of
the magnitude or angular distribution or neutrino luminosity with mass-ratio.
The heavier neutrino species have a luminosity dependence on mass-ratio but an
angular distribution which does not change with mass-ratio.
