On the possibility to measure galactic photons at the altitude of the Pierre Auger Observatory

Abstract

The presence of galactic sources displaying a power-law dependence in their gamma-ray fluxes has been recently reported by gamma-ray observatories such as LHAASO and HAWC. This exciting discovery, with a few sources showing no cutoff in their flux, has the potential to enable measurements of photon fluxes at energies even higher than 10 15 eV. To measure the tails of the energy spectra of these sources, we investigate the capabilities of a new dense array of water-Cherenkov detectors, the Project for Extreme PeVatron Sources (PEPS). To distinguish primary photons from the overwhelming cosmic-rays background, we investigate the performance of a detector that optically divides the water volume to separate the muonic component of air showers from the electromagnetic one. The expected sensitivity of these layered surface detectors, covering a 2 km 2 area at the site of the Pierre Auger Observatory, is presented. With the potential to make groundbreaking discoveries, such an array might represent a promising area of research in gammaray astronomy.