Gravitational Radiation from Nonaxisymmetric Instability in a Rotating Star

TL;DR

This paper presents the first calculations of gravitational waves emitted by a rapidly rotating star undergoing nonaxisymmetric instability, showing significant deformation and measurable gravitational radiation at kilohertz frequencies.

Contribution

It provides the first detailed computation of gravitational radiation from nonaxisymmetric instability in a rotating star, including deformation, energy, and angular momentum loss estimates.

Findings

Star deforms into a bar shape, shedding 4% of mass and 17% of angular momentum.

Gravitational waves at ~4 kHz with amplitude ~2×10⁻²² at Virgo Cluster distance.

Radiates about 0.1% of its energy and 0.7% of its angular momentum.

Abstract

We present the first calculations of the gravitational radiation produced by nonaxisymmetric dynamical instability in a rapidly rotating compact star. The star deforms into a bar shape, shedding $\sim 4\%$ of its mass and $\sim 17\%$ of its angular momentum. The gravitational radiation is calculated in the quadrupole approximation. For a mass $M \sim 1.4$ M$_{\odot}$ and radius $R \sim 10$ km, the gravitational waves have frequency $\sim 4$ kHz and amplitude $h \sim 2 \times 10^{-22}$ at the distance of the Virgo Cluster. They carry off energy $\Delta E/M \sim 0.1\%$ and radiate angular momentum $\Delta J/J \sim 0.7\%$.