| Abstract : | Accretion in spinning neutron stars can lead to a starquake. In this work, we try to understand how continuous gravitational wave signals generated by a misaligned neutron star change under the influence of starquakes. The neutron star we consider here has a magnetic mountain near its magnetic pole. As the star is rotating about its rotational axis, the change in the mass quadrupole moment will generate continuous gravitational wave signal. Accretion of the binary companion fragments in such a system can lead to a spin-up process. Upon reaching a certain breaking frequency, this spin-up process can lead to starquakes. In this work, we show how the pre-existing gravitational wave signal from such a star can change due to starquakes. We show that for a spherically symmetric misaligned star, the amplitude of the gravitational wave signal increases after starquake. Whereas after starquake, a pulsar that is already in a deformed state tends to reduce the amplitude of gravitational wave signal. These results can be explained by the symmetry and the distribution of the accreted mass on the surface of the star. When accumulating mass on its magnetic pole, a spherical star will increase its ellipticity, i.e., the star will be more deformed compared to its previous state. Hence, the amplitude increases for the signal and for a star which is already deformed, the accumulation occurs such that it tends to make the star spherical, reducing the amplitude of the gravitational wave signal. |
