Effects of Nontrivial Topology on Neutron Star Rotation and its Potential Observational Implications

TL;DR

This paper explores how one-dimensional topological defects, like cosmic strings, trapped within neutron stars could cause rotational glitches and generate gravitational waves, providing a new perspective on pulsar irregularities and their detectability.

Contribution

It introduces a novel mechanism linking topological defects to pulsar glitches and gravitational wave signals, suggesting observational tests for the presence of cosmic strings in neutron stars.

Findings

Topological defects can induce abrupt changes in neutron star rotation.

Coupling of string tension with angular velocity can produce detectable gravitational waves.

Predicted gravitational wave signatures are within advLIGO noise sensitivity.

Abstract

Rotational irregularities are one of the prominent observational features that most pulsars exhibit. These glitches, which are sudden increases in spin angular velocity, remains an open problem. In this study, we have investigated the potential role of nontrivial topological defects, specifically in the form of Nambu-goto-type CSs, and its connection to spin irregularities. Such CSs which are one-dimensional topological defects may be formed during various symmetry-breaking and phase transition scenarios and can interact with the neutron stars. In this work, we see that the appearance of such topological defects trapped within the core can lead to the coupling of the string tension with the angular velocity, leading to the abrupt rotational changes observed as pulsar glitches. We have further studied how these coupling may generate detectable gravitational waves as a mixture of continuous and burst signals. The evolution of cusps of CSs trapped within neutron stars and the neutron star's mass quadruple moment change due to rotation could produce distinctive gravitational wave signatures, well within the noise cutoff of advLIGO. Our study highlights a potential connection between topological defects, pulsar glitches, and gravitational wave emissions, offering a possible avenue for observationally testing the presence of CSs and their astrophysical effects.