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

Abstract

The vulnerability of standard detection methods for long-duration quasi-monochromatic gravitational waves from non-axisymmetric rotating neutron stars ('continuous waves', CWs) to single-detector instrumental artifacts was addressed in past work [Keitel, Prix, Papa, Leaci and Siddiqi, 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 this approach to cover transient 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. Focusing on the time-scale of a single segment in the semicoherent search, Bayesian model selection yields a generalized detection statistic that does not add significant computational cost. On simulated data, we find it to increase sensitivity towards tCWs, without sacrificing sensitivity to classical CW signals, and still being robust to transient or persistent single-detector instrumental artifacts