Gravitational waves from r-mode oscillations of stochastically accreting neutron stars

Abstract

r-mode oscillations in rotating neutron stars are a source of continuous gravitational radiation. We investigate the excitation of r-modes by the mechanical impact on the neutron star surface of stochastically accreted clumps of matter, assuming that the Chandrasekhar-Friedman-Schutz instability is not triggered. The star is idealized as a slowly rotating, unmagnetized, one-component fluid with a barotropic equation of state in Newtonian gravity. It is found that the r-mode amplitude depends weakly on the equation of state but sensitively on the rotation frequency. The gravitational wave strain implicitly depends on the equation of state through the damping time-scale. The root-mean-square s..