Improvements in Gravitational-Wave Sky Localization with Expanded Networks of Interferometers

TL;DR

This paper analyzes how expanding the global network of gravitational-wave detectors improves the accuracy of localizing neutron star and black hole merger sources, enhancing multi-messenger astronomy.

Contribution

It provides the first detailed study of sky localization improvements for neutron star--black hole binaries as the detector network expands over the next decade.

Findings

Median localization improves from 60 deg$^2$ with three detectors to 11 deg$^2$ with five detectors.

Expanded detector networks significantly enhance the ability to identify electromagnetic counterparts.

Study includes simulations of neutron star--black hole mergers for future network configurations.

Abstract

A milestone of multi-messenger astronomy has been achieved with the detection of gravitational waves from a binary neutron star merger accompanied by observations of several associated electromagnetic counterparts. Joint observations can reveal details of the engines that drive the electromagnetic and gravitational-wave emission. However, locating and identify an electromagnetic counterparts to a gravitational-wave event is heavily reliant on localization of the source through gravitational-wave information. We explore the sky localization of a simulated set of neutron star mergers as the worldwide network of gravitational-wave detectors evolves through the next decade, performing the first such study for neutron star -- black hole binary sources. Currently, three detectors are observing with additional detectors in Japan and India expected to become operational in the coming years. With three detectors, we recover a median neutron star -- black hole binary sky localization of 60 deg$^2$ at the 90\% credible level. As all five detectors become operational, sources can be localized to a median of 11 deg$^2$ on the sky.