Establishing the significance of continuous gravitational-wave detections from known pulsars

TL;DR

This paper introduces a novel method for assessing the statistical significance of continuous gravitational wave signals from known pulsars, using sky-shifting to empirically estimate noise backgrounds without assuming Gaussian noise.

Contribution

The paper presents a sky-shifting technique that improves significance estimation in targeted gravitational wave searches, enhancing detection confidence without relying on Gaussian noise assumptions.

Findings

Method outperforms traditional significance estimation strategies.

Effective in non-Gaussian noise conditions.

Demonstrated success with simulated and real data injections.

Abstract

We present a method for assigning a statistical significance to detection candidates in targeted searches for continuous gravitational waves from known pulsars, without assuming the detector noise is Gaussian and stationary. We take advantage of the expected Doppler phase modulation of the signal induced by Earth's orbital motion, as well as the amplitude modulation induced by Earth's spin, to effectively blind the search to real astrophysical signals from a given location in the sky. We use this "sky-shifting" to produce a large number of noise-only data realizations to empirically estimate the background of a search and assign detection significances, in a similar fashion to the use of timeslides in searches for compact binaries. We demonstrate the potential of this approach by means of simulated signals, as well as hardware injections into real detector data. In a study of simulated signals in non-Gaussian noise, we find that our method outperforms another common strategy for evaluating detection significance. We thus demonstrate that this and similar techniques have the potential to enable a first confident detection of continuous gravitational waves.