# Dispersion and decay of collective modes in neutron star cores

## TL;DR

This paper calculates the frequencies of collective modes in neutron star cores, considering neutron, proton, and electron interactions, and assesses their impact on thermal conductivity, highlighting the effects of Landau damping and entrainment.

## Contribution

It provides a detailed analysis of collective mode frequencies in neutron star cores, incorporating hydrodynamic and collisionless electron models, and evaluates their influence on thermal conductivity.

## Key findings

- Landau damping significantly affects mode dispersion.
- Mode frequencies are sensitive to neutron-proton entrainment.
- Collective modes contribute notably to thermal conductivity.

## Abstract

We calculate the frequencies of collective modes of neutrons, protons and electrons in the outer core of neutron stars. The neutrons and protons are treated in a hydrodynamic approximation and the electrons are regarded as collisionless. The coupling of the nucleons to the electrons leads to Landau damping of the collective modes and to significant dispersion of the low-lying modes. We investigate the sensitivity of the mode frequencies to the strength of entrainment between neutrons and protons, which is not well characterized. The contribution of collective modes to the thermal conductivity is evaluated.