Robust semicoherent searches for continuous gravitational waves with noise and signal models including hours to days long transients

TL;DR

This paper enhances semicoherent gravitational wave searches by modeling short-duration transients and artifacts, improving robustness and sensitivity to continuous and transient signals from neutron stars without significant additional computational cost.

Contribution

It introduces an extended noise model for transient disturbances and a Bayesian detection statistic to improve sensitivity to transient signals in standard searches.

Findings

Increased robustness against transient and persistent artifacts.

Enhanced sensitivity to transient signals of varying durations.

Maintained sensitivity to classical continuous waves.

Abstract

The vulnerability to single-detector instrumental artifacts in standard detection methods for long-duration quasimonochromatic gravitational waves from nonaxisymmetric rotating neutron stars [continuous waves (CWs)] was addressed in past work [D. Keitel et al., Phys. Rev. D 89, 064023 (2014).] by a Bayesian approach. An explicit model of persistent single-detector disturbances led to a generalized detection statistic with improved robustness against such artifacts. Since many strong outliers in semicoherent searches of LIGO data are caused by transient disturbances that last only a few hours, we extend the noise model to cover such limited-duration disturbances, and demonstrate increased robustness in realistic simulated data. Besides long-duration CWs, neutron stars could also emit transient signals which, for a limited time, also follow the CW signal model (tCWs). As a pragmatic alternative to specialized transient searches, we demonstrate how to make standard semicoherent CW searches more sensitive to transient signals. Considering tCWs in a single segment of a semicoherent search, Bayesian model selection yields a new detection statistic that does not add significant computational cost. On simulated data, we find that it increases sensitivity towards tCWs, even of varying durations, while not sacrificing sensitivity to classical CW signals, and still being robust to transient or persistent single-detector instrumental artifacts.