# Damping of density oscillations in neutrino-transparent nuclear matter

## TL;DR

This paper calculates the damping times of density oscillations in nuclear matter relevant to neutron star mergers, considering temperature and density effects on bulk viscosity due to weak interactions.

## Contribution

It provides new estimates of bulk viscous damping times at various densities and temperatures, extending previous low-temperature models to more realistic merger conditions.

## Key findings

- Damping times range from 5 to 20 ms for 1 kHz oscillations.
- Bulk viscosity can significantly influence neutron star merger dynamics.
- Higher frequency oscillations damp faster, affecting merger evolution.

## Abstract

We calculate the bulk-viscous dissipation time for adiabatic density oscillations in nuclear matter at densities of 1-7 times nuclear saturation density and at temperatures ranging from 1 MeV, where corrections to previous low-temperature calculations become important, up to 10 MeV, where the assumption of neutrino transparency is no longer valid. Under these conditions, which are expected to occur in neutron star mergers, damping of density oscillations arises from beta equilibration via weak interactions. We find that for 1 kHz oscillations the shortest dissipation times are in the 5 to 20 ms range, depending on the equation of state, which means that bulk viscous damping could affect the dynamics of a neutron star merger. For higher frequencies the dissipation time can be even shorter.