The First Two Years of Electromagnetic Follow-Up with Advanced LIGO and Virgo

TL;DR

This paper models the early capabilities of Advanced LIGO and Virgo in detecting and localizing gravitational wave sources, emphasizing the importance of electromagnetic follow-up during the first two years of operation.

Contribution

It provides detailed predictions of detection rates and sky localization accuracy for binary neutron star mergers during the initial LIGO/Virgo observing runs, highlighting the role of rapid localization.

Findings

Rapid sky localization is as accurate as full parameter estimation for most events.

Sky localization improves from ~500 to ~200 square degrees between 2015 and 2016.

Advanced Virgo significantly enhances sky localization despite lower sensitivity.

Abstract

We anticipate the first direct detections of gravitational waves (GWs) with Advanced LIGO and Virgo later this decade. Though this groundbreaking technical achievement will be its own reward, a still greater prize could be observations of compact binary mergers in both gravitational and electromagnetic channels simultaneously. During Advanced LIGO and Virgo's first two years of operation, 2015 through 2016, we expect the global GW detector array to improve in sensitivity and livetime and expand from two to three detectors. We model the detection rate and the sky localization accuracy for binary neutron star (BNS) mergers across this transition. We have analyzed a large, astrophysically motivated source population using real-time detection and sky localization codes and higher-latency parameter estimation codes that have been expressly built for operation in the Advanced LIGO/Virgo era. We show that for most BNS events the rapid sky localization, available about a minute after a detection, is as accurate as the full parameter estimation. We demonstrate that Advanced Virgo will play an important role in sky localization, even though it is anticipated to come online with only one-third as much sensitivity as the Advanced LIGO detectors. We find that the median 90% confidence region shrinks from ~500 square degrees in 2015 to ~200 square degrees in 2016. A few distinct scenarios for the first LIGO/Virgo detections emerge from our simulations.