# The g-mode spectrum of reactive neutron star cores

## TL;DR

This paper investigates how nuclear reactions affect the gravity g-mode spectrum in neutron stars, showing that these modes disappear when nuclear reaction timescales exceed oscillation periods, with implications for neutron star astrophysics.

## Contribution

It develops a framework for incorporating finite-time nuclear reactions into neutron star oscillation models and links this to bulk viscosity concepts.

## Key findings

- High-order g-modes vanish when nuclear reaction timescales are long.
- Framework connects nuclear reactions with bulk viscosity in neutron star oscillations.
- Absence of certain g-modes impacts astrophysical models of neutron stars.

## Abstract

We discuss the impact of nuclear reactions on the spectrum of gravity g-modes of a mature neutron star, demonstrating the anticipated disappearance of these modes when the timescale associated with the oscillations is longer than that of nuclear reactions. This is the expected result, but different aspects of the demonstration may be relevant for related problems in neutron star astrophysics. In particular, we develop the framework required for an explicit implementation of finite-time nuclear reactions in neutron star oscillation problems and demonstrate how this formulation connects with the usual bulk viscosity prescription. We also discuss implications of the absence of very high order g-modes for problems of astrophysical relevance.