Search for photons above 1019eV with the surface detector of the Pierre Auger Observatory

THE PIERRE AUGER COLLABORATION; SILVIA MOLLERACH

JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS

IOP PUBLISHING LTD

Año: 2023 vol. 2023

1475-7516

We use the surface detector of the Pierre Auger Observatory to search for airshowers initiated by photons with an energy above 10 19 eV. Photons in the zenith angle rangefrom 30 ◦ to 60 ◦ can be identified in the overwhelming background of showers initiated bycharged cosmic rays through the broader time structure of the signals induced in the water-Cherenkov detectors of the array and the steeper lateral distribution of shower particlesreaching ground. Applying the search method to data collected between January 2004 andJune 2020, upper limits at 95% CL are set to an E −2 diffuse flux of ultra-high energyphotons above 10 19 eV, 2×10 19 eV and 4×10 19 eV amounting to 2.11×10 −3 , 3.12×10 −4 and1.72×10 −4 km −2 sr −1 yr −1 , respectively. While the sensitivity of the present search around2 × 10 19 eV approaches expectations of cosmogenic photon fluxes in the case of a pure-protoncomposition, it is one order of magnitude above those from more realistic mixed-compositionmodels. The inferred limits have also implications for the search of super-heavy dark matterthat are discussed and illustrated.