Gravitational waves from small spin-up and spin-down events of neutron stars

TL;DR

This paper proposes a testable model linking small neutron star spin variations to gravitational wave emissions from non-axisymmetric f-modes, which could be validated with future third-generation detectors.

Contribution

It introduces a novel model connecting small neutron star spin changes to gravitational wave signals from f-mode oscillations, providing a new way to understand these events.

Findings

Model predicts gravitational wave signals from small spin events.

Future detectors can test the model's predictions.

Model offers a potential explanation for glitch and anti-glitch phenomena.

Abstract

It was recently reported that there exists a population of "glitch candidates" and "anti-glitch candidates" which are effectively small spin-ups and spin-downs of a neutron star with magnitudes smaller than those seen in typical glitches. The physical origin of these small events is not yet understood. In this paper, we outline a model that can account for the changes in spin, and crucially, is independently testable with gravitational wave observations. In brief, the model posits that small spin-up/spin-down events are caused by the excitation and decay of non-axisymmetric $f$-modes which radiate angular momentum away in a burst-like way as gravitational waves. The model takes the change in spin frequency as an input and outputs the initial mode amplitude and the signal-to-noise ratio achievable from gravitational wave detectors. We find that the model presented here will become falsifiable once 3rd generation gravitational wave detectors, like the Einstein Telescope and Cosmic Explorer, begin taking data.