Stochastic background of gravitational waves generated by a cosmological population of young, rapidly rotating neutron stars

Abstract

We estimate the spectral properties of the stochastic background of gravitational radiation emitted by a cosmological population of hot, young, rapidly rotating neutron stars. Their formation rate as a function of redshift is deduced from an observation-based determination of the star formation history in the Universe, and the gravitational energy is assumed to be radiated during the spin-down phase associated with the newly discovered r-mode instability. We calculate the overall signal produced by the ensemble of such neutron stars, assuming various cosmological backgrounds. We find that the spectral strain amplitude has a maximum ≈(2-4) × 10-26 Hz-1/2 , at frequencies ≈(30-60) Hz, while the corresponding closure density, h2 ΩGW, has a maximum amplitude plateau of ≈(2.2-3.3) × 10-8 in the frequency range (500-1700) Hz. We compare our results with a preliminary analysis done by Owen et al., and discuss the detectability of this background.