Detection and localization of continuous gravitational waves with pulsar timing arrays: the role of pulsar terms

TL;DR

This paper introduces a faster Frequentist method for detecting and localizing continuous gravitational waves with pulsar timing arrays, emphasizing the importance of including pulsar terms for accurate results.

Contribution

The work presents a new detection and localization method that incorporates pulsar terms, improving speed and accuracy over existing techniques.

Findings

Including pulsar terms improves sky localization accuracy.

Full-signal search slightly increases detection probability.

Strong signals may allow better pulsar distance estimation.

Abstract

A pulsar timing array is a Galactic-scale detector of nanohertz gravitational waves (GWs). Its target signals contain two components: the `Earth term' and the `pulsar term' corresponding to GWs incident on the Earth and pulsar respectively. In this work we present a Frequentist method for the detection and localization of continuous waves that takes into account the pulsar term and is significantly faster than existing methods. We investigate the role of pulsar terms by comparing a full-signal search with an Earth-term-only search for non-evolving black hole binaries. By applying the method to synthetic data sets, we find that (i) a full-signal search can slightly improve the detection probability (by about five percent); (ii) sky localization is biased if only Earth terms are searched for and the inclusion of pulsar terms is critical to remove such a bias; (iii) in the case of strong detections (with signal-to-noise ratio $\gtrsim$ 30), it may be possible to improve pulsar distance estimation through GW measurements.