Estimating parameters of coalescing compact binaries with a detector network including LIGO Australia

TL;DR

Adding an Australian detector to the gravitational-wave network significantly improves source localization, especially sky position, which is vital for electromagnetic follow-up observations.

Contribution

This study demonstrates the benefits of including an Australian detector in the gravitational-wave network for enhanced parameter estimation of binary mergers.

Findings

Sky localization improves by a factor of ~4 with the Australian detector.

Parameter degeneracies are reduced, leading to better source characterization.

Distance and inclination estimates see modest improvements.

Abstract

One of the goals of gravitational-wave astronomy is simultaneous detection of gravitational-wave signals from merging compact-object binaries and the electromagnetic transients from these mergers. With the next generation of advanced ground-based gravitational wave detectors under construction, we examine the benefits of the proposed extension of the detector network to include a fourth site in Australia in addition to the network of Hanford, Livingston and Cascina sites. Using Bayesian parameter-estimation analyses of simulated gravitational-wave signals from a range of coalescing-binary locations and orientations, we study the improvement in parameter estimation. We find that an Australian detector can break degeneracies in several parameters; in particular, the localization of the source on the sky is improved by a factor of ~4, with more modest improvements in distance and binary inclination estimates. This enhanced ability to localize sources on the sky will be crucial in any search for electromagnetic counterparts to detected gravitational-wave signals.