Search for UHE Photons from Gravitational Wave Sources with the Pierre Auger Observatory

TL;DR

This study searches for ultra-high-energy photons coinciding with gravitational wave events using the Pierre Auger Observatory, setting the first limits on such photons and constraining energy transfer in neutron star mergers.

Contribution

It introduces the first search for UHE photons from GW sources and establishes upper limits on photon fluence associated with these events.

Findings

No coincidences found between UHE photons and GW events.

Upper limits on photon fluence are established at ~7 MeV/cm² and ~35 MeV/cm².

Constraints on energy transfer in GW170817 suggest less than 20% of GW energy converted to UHE photons.

Abstract

A search for time-directional coincidences of ultra-high-energy (UHE) photons above 10 EeV with gravitational wave (GW) events from the LIGO/Virgo runs O1 to O3 is conducted with the Pierre Auger Observatory. Due to the distinctive properties of photon interactions and to the background expected from hadronic showers, a subset of the most interesting GW events is selected based on their localization quality and distance. Time periods of 1000 s around and 1 day after the GW events are analyzed. No coincidences are observed. Upper limits on the UHE photon fluence from a GW event are derived that are typically at $\sim$7 MeV cm$^{-2}$ (time period 1000~s) and $\sim$35 MeV cm$^{-2}$ (time period 1 day). Due to the proximity of the binary neutron star merger GW170817, the energy of the source transferred into UHE photons above 40 EeV is constrained to be less than 20% of its total gravitational wave energy. These are the first limits on UHE photons from GW sources.