Reconstruction of source location in a network of gravitational wave interferometric detectors

TL;DR

This paper presents a method for reconstructing the sky position of gravitational wave sources using a network of interferometric detectors, achieving about 1 degree accuracy for high SNR signals and demonstrating improvements with additional detectors.

Contribution

It introduces a chi-squared minimization technique for source localization and analyzes the impact of network geometry on reconstruction accuracy.

Findings

Mean angular error about 1 degree for SNR>4.5 in all detectors

Adding more detectors reduces blind spots and improves accuracy

Six detectors can localize sources within 1 degree for 99% of the sky

Abstract

This paper deals with the reconstruction of the direction of a gravitational wave source using the detection made by a network of interferometric detectors, mainly the LIGO and Virgo detectors. We suppose that an event has been seen in coincidence using a filter applied on the three detector data streams. Using the arrival time (and its associated error) of the gravitational signal in each detector, the direction of the source in the sky is computed using a chi^2 minimization technique. For reasonably large signals (SNR>4.5 in all detectors), the mean angular error between the real location and the reconstructed one is about 1 degree. We also investigate the effect of the network geometry assuming the same angular response for all interferometric detectors. It appears that the reconstruction quality is not uniform over the sky and is degraded when the source approaches the plane defined by the three detectors. Adding at least one other detector to the LIGO-Virgo network reduces the blind regions and in the case of 6 detectors, a precision less than 1 degree on the source direction can be reached for 99% of the sky.