The H.E.S.S. Gravitational Wave Rapid Follow-up Program

Abstract

Gravitational Wave (GW) events are physical processes that significantly perturbate space-time, e.g. compact binary coalescenses, causing the production of GWs. The detection of GWs by a worldwide network of advanced interferometers offer unique opportunities for multi-messenger searches and electromagnetic counterpart associations. While carrying extremely useful information, searches for associated electromagnetic emission are challenging due to large sky localisation uncertainties provided by the current GW observatories LIGO and Virgo. Here we present the methods and procedures used within the High Energy Stereoscopic System (H.E.S.S.) in searches for very-high-energy (VHE) gamma-ray emission associated to the emission of GWs from extreme events. To do so we create several algorithms dedicated to schedule GW follow-up observations by creating optimized pointing paterns. We describe algorithms using 2-dimensional GW localisation information and algorithms correlating the galaxy distribution in the local universe, by using galaxy catalogs, with the 3-dimensional GW localisation information and evaluate their performances. The H.E.S.S. automatic GW follow-up chain, described in this paper, is optimized to initiate GW follow-up observations within less than 1 minute after the alert reception. These developements allowed H.E.S.S. observations of 6 GW events out of the 67 non-retracted GW events detected during the first three observation runs of LIGO and Virgo reaching VHE $\gamma$-ray coverages of up to 70% of the GW localisation.

27 pages, 15 figures

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Cited by in corpus (10)

• GWTC-3: Compact Binary Coalescences Observed by LIGO and Virgo During the Second Part of the Third Observing Run
• Astro-COLIBRI -- The COincidence LIBrary for Real-time Inquiry for multimessenger astrophysics
• The H.E.S.S. transients follow-up system
• H.E.S.S. follow-up observations of Binary Black Hole Coalescence events during the second and third Gravitational Waves observing runs of Advanced LIGO and Advanced Virgo
• Astro-COLIBRI 2 -- an advanced platform for real-time multi-messenger discoveries
• Investigating the detection rates and inference of gravitational-wave and radio emission from black hole neutron star mergers
• Cross-Observatory Coordination with tilepy: A Novel Tool for Observations of Multi-Messenger Transient Events
• The Transients Handler System for the Cherenkov Telescope Array Observatory
• Modelling the host galaxies of binary compact object mergers with observational scaling relations
• Chasing Gamma-Ray Signals from Binary Neutron Star Coalescences with the Cherenkov Telescope Array: Prospects and Observing Strategies