Gravitational radiation from the r-mode instability

TL;DR

This paper discusses the potential detectability of gravitational waves emitted by r-mode instabilities in rotating neutron stars, providing estimates based on simulations and analytical models for current and future detectors.

Contribution

It offers the first detailed estimates of gravitational wave signals from r-mode instabilities, including an analytical expression for optimal detection S/N.

Findings

Gravitational waves from r-modes are detectable at 20 Mpc with current detectors.

The gravitational wave signal is monochromatic near 960 Hz with about 100 seconds duration.

Optimal S/N ranges from 1.2 to 12.0 depending on detector configuration.

Abstract

The instability in the r-modes of rotating neutron stars can (in principle) emit substantial amounts of gravitational radiation (GR) which might be detectable by LIGO and similar detectors. Estimates are given here of the detectability of this GR based the non-linear simulations of the r-mode instability by Lindblom, Tohline and Vallisneri. The burst of GR produced by the instability in the rapidly rotating 1.4 solar mass neutron star in this simulation is fairly monochromatic with frequency near 960 Hz and duration about 100 s. A simple analytical expression is derived here for the optimal S/N for detecting the GR from this type of source. For an object located at a distance of 20 Mpc we estimate the optimal S/N to be in the range 1.2 to about 12.0 depending on the LIGO II configuration.