A search for ultra-high-energy photons at the Pierre Auger Observatory exploiting air-shower universality

Discussion timeslot (ZOOM-Meeting): 16. July 2021 - 18:00
ZOOM-Meeting URL: https://icrc2021.desy.de/pf_access_abstracts
Corresponding Session: https://icrc2021-venue.desy.de/channel/Presenter-Forum-1-Evening-All-Categories/48
Abstract:
'The Pierre Auger Observatory is the most sensitive detector to primary photons with energiesrnabove ∼ 0.2 EeV. It measures extensive air-showers using a hybrid technique that combinesrna fluorescence detector (FD) with a ground array of particle detectors (SD). The signaturesrnof a photon-induced air-shower are a larger atmospheric depth at the shower maximumrn(Xmax) and a steeper lateral distribution function, along with a lower number of muons withrnrespect to the bulk of hadron-induced background. Using observables measured by thernFD and SD, three photon searches in different energy bands are performed. In particular,rnbetween 1 and 10 EeV, a new analysis technique has been developed by combining the FDrnbased measurement of Xmax with the SD signal through a parameter related to its muonrncontent, derived from the universality of the air-showers. This technique has led to a betterrnphoton/hadron separation and, consequently, to a higher search sensitivity, resulting in arntighter upper limit than before. The outcome of this new analysis is presented here, alongrnwith previous results below 1 EeV and above 10 EeV. From the data collected by the PierrernAuger Observatory in about 15 years of operation, the most stringent constraints on thernfraction of photons in the cosmic flux are set over about three decades in energy.'

Authors: Pierpaolo Savina
Co-Authors: For the Pierre Auger Collaboration
Collaboration: Auger

Indico-ID: 1043
Proceeding URL: https://pos.sissa.it/395/373