Implementation and testing of the first prompt search for gravitational wave transients with electromagnetic counterparts

Abstract

Article published by EDP Sciences A124, page 1 of 15 A&A 539, A124 (2012) ABSTRACT Aims. A transient astrophysical event observed in both gravitational wave (GW) and electromagnetic (EM) channels would yield rich scientific rewards. A first program initiating EM follow-ups to possible transient GW events has been developed and exercised by the LIGO and Virgo community in association with several partners. In this paper, we describe and evaluate the methods used to promptly identify and localize GW event candidates and to request images of targeted sky locations. Methods. During two observing periods (Dec. 17, 2009 to Jan. 8, 2010 and Sep. 2 to Oct. 20, 2010, a low-latency analysis pipeline was used to identify GW event candidates and to reconstruct maps of possible sky locations. A catalog of nearby galaxies and Milky Way globular clusters was used to select the most promising sky positions to be imaged, and this directional information was delivered to EM observatories with time lags of about thirty minutes. A Monte Carlo simulation has been used to evaluate the low-latency GW pipeline's ability to reconstruct source positions correctly.Results. For signals near the detection threshold, our low-latency algorithms often localized simulated GW burst signals to tens of square degrees, while neutron star/neutron star inspirals and neutron star/black hole inspirals were localized to a few hundred square degrees. Localization precision improves for moderately stronger signals. The correct sky location of signals well above threshold and originating from nearby galaxies may be observed with ∼50% or better probability with a few pointings of wide-field telescopes.

Prospects for Observing and Localizing Gravitational-Wave Transients with Advanced LIGO and Advanced Virgo

“…A prompt notice of a potential GW transient by LIGO-Virgo might enable follow-up observations in the electromagnetic spectrum. A first follow-up program including low-latency analysis, event candidate selection, position reconstruction and the sending of alerts to several observing partners (optical, X-ray, and radio) was implemented and exercised during the 2009–2010 LIGO-Virgo science run [16, 15, 53]. Latencies of less than 1 hour were achieved and we expect to improve this in the advanced-detector era.…”

SUPPLEMENT: “LOCALIZATION AND BROADBAND FOLLOW-UP OF THE GRAVITATIONAL-WAVE TRANSIENT GW150914” (2016, ApJL, 826, L13)

“…The first gravitational-wave (GW)-triggered electromagnetic (EM) observations were carried out during the 2009-2010 science run of the initial LIGO and Virgo detectors (Abadie et al 2012b), featuring real-time searches for unmodeled GW bursts and compact binary coalescences (CBCs; Abadie et al 2012aAbadie et al , 2012b. GW candidates were identified-typically within 30 minutes-and their inferred sky locations were used to plan follow-up observations with over a dozen optical and radio telescopes on the ground plus the Swift satellite (Gehrels et al 2004).…”

Localization and Broadband Follow-Up of the Gravitational-Wave Transient Gw150914

“…The first campaign to find EM counterparts triggered by lowlatency GW event candidates was carried out with the initial (Abadie et al 2012a(Abadie et al , 2012bEvans et al 2012;Aasi et al 2014). In preparing for Advanced detector operations, the LIGO and Virgo collaborations worked with the broader astronomy community to set up an evolved and greatly expanded EM follow-up program.…”