Gravitational waves from non-radial perturbations in neutron stars

Abstract

In the present work, we explore the Rossby mode perturbations in case of neutron stars as sources of continuous gravitational waves. The intensity and time evolution of the emitted gravitational waves in terms of the amplitude of the strain tensor are estimated in the slow rotation approximation using β-equilibrated neutron star matter obtained from density dependent M3Y effective interaction. For a wide range of neutron star masses, the fiducial gravitational and various viscous time scales, the critical frequencies and the time evolutions of the frequencies are calculated. Unlike other non-radial perturbations, amplitude of Rossby mode perturbation increases due to the emission of gravitational waves which carry angular momentum of the star to infinity. Hence, existence of such perturbation in a star implies a positive rate of change in the angular momentum transfer. It, therefore, implies that for a particular neutron star, the intensity of gravitational wave emission increases with time until the angular frequency reduces down to a critical value below which the star stops emitting radiation.