MURCA driven Bulk viscosity in neutrino trapped baryonic matter
Abstract
We examine bulk viscosity, taking into account trapped neutrinos in baryonic matter, in the context of binary neutron star mergers. Following the merging event, the binary star can yield a remnant compact object with densities up to $5$ nuclear saturation density and temperature upto $50$ MeV resulting in the retention of neutrinos. We employ two relativistic mean field models, NL3 and DDME2, to describe the neutrinotrapped baryonic matter. The dissipation coefficient is determined by evaluating the Modified URCA interaction rate in the dense baryonic medium, and accounting for perturbations caused by density oscillations. We observe the resonant behavior of bulk viscosity as it varies with the temperature of the medium. The bulk viscosity peak remains within the temperature range of $\sim 1350$ MeV, depending upon the underlying equation of states and lepton fractions. This temperature range corresponds to the relevant domain of binary neutron star mergers. We also note that in presence of neutrinos in the medium the bulk viscosity peak shifts towards higher temperature and the peak value of bulk viscosity also changes. The time scale of viscous dissipation is dictated by the betaoffequilibrium susceptibilities derived from the nuclear equation of state. The resulting viscous decay time scale ranges from $32100$ milliseconds, which aligns with the order of magnitude of the postmerger object's survival time in some specific scenarios.
 Publication:

arXiv eprints
 Pub Date:
 June 2024
 DOI:
 10.48550/arXiv.2406.08978
 arXiv:
 arXiv:2406.08978
 Bibcode:
 2024arXiv240608978S
 Keywords:

 Nuclear Theory;
 Astrophysics  High Energy Astrophysical Phenomena;
 High Energy Physics  Phenomenology
 EPrint:
 27 pages, 10 figures