Search for Ultra-High Energy Photons with the Pierre Auger Observatory

TL;DR

This paper reports recent results from the Pierre Auger Observatory in searching for ultra-high energy photons above 100 PeV, constraining astrophysical models and exploring future detector upgrades.

Contribution

It presents new limits on diffuse and directional ultra-high energy photon fluxes, and discusses the potential of the AugerPrime upgrade for future neutral particle searches.

Findings

Diffuse limits constrain top-down models and approach GZK photon flux predictions.

Directional limits exclude electromagnetic flux continuation from TeV sources at >5σ significance.

Prospects for future searches with the AugerPrime upgrade are discussed.

Abstract

The Pierre Auger Observatory, located in Argentina, provides an unprecedented integrated aperture for the search of photons with energy above 100 PeV. In this contribution recent results are presented including the diffuse search for photons and the directional search for photon point sources. The derived limits are of considerable astrophysical interest: Diffuse limits place severe constraints on top-down models and start to touch the predicted GZK photon flux range while directional limits can exclude the continuation of the electromagnetic flux from measured TeV sources with a significance of more than 5$\sigma$. Finally, prospects of neutral particle searches for the upcoming detector upgrade AugerPrime are highlighted.