Search method for long-duration gravitational-wave transients from neutron stars

TL;DR

This paper presents a novel search method for long-duration gravitational-wave signals from neutron stars, extending traditional continuous-wave searches to transient signals with finite duration, and demonstrates improved sensitivity through simulations.

Contribution

The authors develop a Bayesian detection method for long-duration transient gravitational waves from neutron stars, incorporating finite start-time and duration, and compare its performance to existing approaches.

Findings

Outperforms traditional maximum-likelihood methods in sensitivity

Efficient implementation for wide parameter-space searches

Effective for both directed and wide-parameter searches

Abstract

We introduce a search method for a new class of gravitational-wave signals, namely long-duration O(hours - weeks) transients from spinning neutron stars. We discuss the astrophysical motivation from glitch relaxation models and we derive a rough estimate for the maximal expected signal strength based on the superfluid excess rotational energy. The transient signal model considered here extends the traditional class of infinite-duration continuous-wave signals by a finite start-time and duration. We derive a multi-detector Bayes factor for these signals in Gaussian noise using $\F$-statistic amplitude priors, which simplifies the detection statistic and allows for an efficient implementation. We consider both a fully coherent statistic, which is computationally limited to directed searches for known pulsars, and a cheaper semi-coherent variant, suitable for wide parameter-space searches for transients from unknown neutron stars. We have tested our method by Monte-Carlo simulation, and we find that it outperforms orthodox maximum-likelihood approaches both in sensitivity and in parameter-estimation quality.