Gravitational radiation of slowly rotating neutron stars

Abstract

The gravitational rotation of slowly rotating neutron stars with rough surfaces is examined. The source of the gravitational waves is assumed to be the energy transferred to the crust of the star during irregular changes in its angular rotation velocity. It is shown that individual pulsars whose angular velocity regularly undergoes glitches will radiate a periodic gravitational signal that can be distinguished from noise by the latest generation of detectors. Simultaneous recording of a gravitational signal and of a glitch in the angular velocity of a pulsar will ensure reliable detection of gravitational radiation.

Gravitational radiation from pulsar glitches

“…acoustic, gravity, and Rossby waves, [25,26] and quasiradial oscillations. [27,28] On the basis of general arguments, invoking the conservation of energy and angular momentum, the gravitational wave strain is predicted to reach h ∼ 10 −26 from pulsars that glitch strongly and frequently, like Vela. [26,27] In this paper, we calculate analytically the gravitational wave signal generated during the relaxation phase of a glitch, when the fluid interior of a neutron star responds to an impulsive, nonaxisymmetric angular acceleration of the crust.…”

Gravitational wave transient signal emission via Ekman pumping in neutron stars during post-glitch relaxation phase

“…In this section, we will calculate the Bessel-Fourier coefficients introduced in (52). We use the orthogonality property of the Bessel functions, which states that Bessel functions are orthogonal with respect to the inner product as follows 29 ,…”

Gravitational radiation of a differentially rotating superfluid neutron star

“…The most promising sources for this type of earthbound detectors are isolated pulsars. The mechanisms for gravitational radiation from isolated pulsars and millisecond pulsars that have been examined thus far [2][3][4] for gravitational waves with frequencies on the order of a kilohertz. This value is far from the limit of sensitivity for currently operating (GEO-600, LIGO) and planned gravitational wave detectors.…”

“…Quasiradial, damped oscillations of a rapidly rotating neutron star have been examined previously [6] and expressions for the gravitational radiation intensity and the damping time for the star's oscillations were obtained. Energy sources for maintaining undamped oscillations of neutron stars have been proposed [2,3].…”

“…A neutron star can acquire a large quadrupole moment during rapid rotation, i.e., the above mechanism may be sufficiently effective for millisecond pulsars [4]. It has been assumed previously [2][3][4] that the angular rotation velocities of the superfluid and normal components of a star differ little from one another, i.e., years for the Crab pulsar) [7,8]. This means that if a hot neutron star rotated with an angular velocity on the order of 6000 s -1 (p~1 ms) when it was born, then as it cools and transforms to a superfluid state its interior may rotate more rapidly than the observed angular velocity of the star's crust [9].…”