Precision of localization of single gravitational-wave source with pulsar timing array

TL;DR

This paper investigates how precise pulsar-distance measurements can significantly improve the angular localization of gravitational wave sources detected by pulsar timing arrays, especially with minimal noise.

Contribution

It demonstrates that incorporating external pulsar distance measurements into PTA analysis can greatly enhance source localization accuracy.

Findings

Few pulsars with 1 pc distance precision improve localization by over 10x

Precise distance info reduces sky localization error significantly

White noise level of 10 ns is considered in the analysis

Abstract

Pulsar Timing Arrays (PTAs) are expected to be able to detect gravitational waves (GWs) from individual supermassive black hole binaries in the near future. In order to identify the host galaxy of a gravitational wave source, the angular resolution of PTAs should be much better than that expected from the conventional methodology of PTAs. We study the potential usefulness of precise pulsar-distance measurements in the determination of the sky location of a single GW source. Precise distance information from external observations such as astrometry by Very Long Baseline Interferometry is incorporated as priors in the PTA analysis and we evaluate the precision of the sky location of a GW source by simulating PTA data of 12 milli-second pulsars with only the GW signal and the Gaussian white noise in the timing residuals. We show that only a few pulsars with a distance precision of 1 pc will improve the precision of the source location by more than 1 order in the presence of white noise of 10 ns.