Neutrino cooling and spin-down of rapidly rotating compact stars

TL;DR

This paper explores how r-mode instabilities in rapidly rotating compact stars influence neutrino cooling and viscosity, affecting their thermal and spin evolution, especially in strange quark stars, with implications for gravitational wave persistence.

Contribution

It introduces a model linking r-mode induced perturbations to neutrino cooling and viscosity in hot compact stars, emphasizing the importance of combined thermal and spin evolution analysis.

Findings

R-mode oscillations significantly impact neutrino cooling rates.

Neutrino cooling influences the spin-down process of compact stars.

Thermal evolution must be considered in gravitational wave predictions.

Abstract

The gravitational-wave instability of r-modes in rapidly rotating compact stars is believed to spin them down to angular frequencies of about a tenth of the Kepler frequency soon after their birth in a Supernova. We point out that the r-mode perturbation also impacts the neutrino cooling and viscosity in hot compact stars via processes that restore weak equilibrium. We illustrate this fact with a simple model of spin-down due to gravitational wave emission in compact stars composed entirely of three-flavor degenerate quark matter (a strange quark star). Non-equilibrium neutrino cooling of this oscillating fluid matter is quantified. Our results imply that a consistent treatment of thermal and spin-frequency evolution of a young and hot compact star is a requisite in estimating the persistence of gravitational waves from such a source.