Nuclear limits on gravitational waves from elliptically deformed pulsars

TL;DR

This paper establishes nuclear physics-based upper limits on gravitational wave amplitudes from elliptically deformed pulsars, linking neutron star matter properties to observable gravitational signals.

Contribution

It provides the first direct nuclear constraint on gravitational wave strain amplitudes from pulsars using recent laboratory data on nuclear symmetry energy.

Findings

Maximal strain amplitude $h_0$ for several millisecond pulsars is in the range of $0.4$ to $1.5 imes 10^{-24}$.

Strain amplitude depends strongly on the neutron star equation of state.

Results connect nuclear physics constraints to gravitational wave predictions.

Abstract

Gravitational radiation is a fundamental prediction of General Relativity. Elliptically deformed pulsars are among the possible sources emitting gravitational waves (GWs) with a strain-amplitude dependent upon the star's quadrupole moment, rotational frequency, and distance from the detector. We show that the gravitational wave strain amplitude $h_0$ depends strongly on the equation of state of neutron-rich stellar matter. Applying an equation of state with symmetry energy constrained by recent nuclear laboratory data, we set an upper limit on the strain-amplitude of GWs produced by elliptically deformed pulsars. Depending on details of the EOS, for several millisecond pulsars at distances $0.18kpc$ to $0.35kpc$ from Earth, the {\it maximal} $h_0$ is found to be in the range of $\sim[0.4-1.5]\times 10^{-24}$. This prediction serves as the first {\it direct} nuclear constraint on the gravitational radiation. Its implications are discussed.