Gravitational Waves From Low Mass Neutron Stars

TL;DR

Low mass neutron stars can support large deformations, making them potentially strong sources of detectable gravitational waves, with significant implications for GW astronomy.

Contribution

This paper demonstrates that low mass neutron stars can sustain much larger ellipticities and quadrupole moments than typical neutron stars, highlighting their potential as prominent GW sources.

Findings

Maximum ellipticities up to 0.01 for low mass stars.

Gravitational wave strain of 2.1×10⁻²⁴ at 1 kpc for a 0.12 M⊙ star.

Advanced LIGO can detect such signals across the Milky Way.

Abstract

Low mass neutron stars may be uniquely strong sources of gravitational waves (GW). The neutron star crust can support large deformations for low mass stars. This is because of the star's weaker gravity. We find maximum ellipticities $\epsilon$ (fractional difference in moments of inertia) that are 1000 times larger, and maximum quadrupole moments $Q_{22}$ over 100 times larger, for low mass stars than for 1.4 $M_\odot$ neutron stars. Indeed, we calculate that the crust can support an $\epsilon$ as large as 0.01 for a minimum mass neutron star. A 0.12 $M_\odot$ star, that is maximally strained and rotating at 100 Hz, will produce a characteristic gravitational wave strain of $h_0=2.1\times 10^{-24}$ at a distance of 1 kpc. The GW detector Advanced LIGO should be sensitive to such objects through out the Milky Way Galaxy.