Bulk viscosity transport coefficients in neutron star mergers

Abstract

We compute first and second-order bulk-viscous transport properties due to weak-interaction processes in npe matter in the neutrino transparent regime. The transport coefficients characterize the out-of-beta-equilibrium pressure corrections, which depend on the weak-interaction rates and the equation of state. We calculate these coefficients for realistic equations of state and show they are sensitive to changes in the nuclear symmetry energy J and its slope L.