Dissipative Kinematics in Binary Neutron Star Mergers

Abstract

We highlight the recent progress in the calculation of transport coefficients pertinent to binary neutron star mergers. Specifically, we analyze the bulk viscosity coefficient driven by both the DURCA and MURCA processes and electron transport coefficients in dense and hot plasma relevant to the merger scenario. The study considers high temperatures (T>6×1010 K) and dense environments (nB∼n0−3n0). Bulk viscosity exhibits resonant behavior, with peak values and Peak positions dependent on particle interaction rates and thermodynamic susceptibilities. Susceptibilities are calculated by modeling the nuclear matter in the density functional approach. The bulk viscosity coefficient peaks at T∼1011 K, with a compression–rarefaction oscillation dissipation time scale of 20–50 ms. Electrical transports incorporate frequency-dependent dynamical screening in quantized electron–ion scattering rates. Consequently, dynamical screening reduces the maxima of electrical and thermal conductivities, shortening corresponding dissipation time scales. These results highlight the crucial role of dissipation coefficients in understanding binary neutron star mergers.