Speaker
Description
The Pierre Auger Observatory is the most sensitive detector to primary photons with energies
above ∼ 0.2 EeV. It measures extensive air-showers using a hybrid technique that combines
a fluorescence detector (FD) with a ground array of particle detectors (SD). The signatures
of a photon-induced air-shower are a larger atmospheric depth at the shower maximum
(Xmax) and a steeper lateral distribution function, along with a lower number of muons with
respect to the bulk of hadron-induced background. Using observables measured by the
FD and SD, three photon searches in different energy bands are performed. In particular,
between 1 and 10 EeV, a new analysis technique has been developed by combining the FD
based measurement of Xmax with the SD signal through a parameter related to its muon
content, derived from the universality of the air-showers. This technique has led to a better
photon/hadron separation and, consequently, to a higher search sensitivity, resulting in a
tighter upper limit than before. The outcome of this new analysis is presented here, along
with previous results below 1 EeV and above 10 EeV. From the data collected by the Pierre
Auger Observatory in about 15 years of operation, the most stringent constraints on the
fraction of photons in the cosmic flux are set over about three decades in energy.
Keywords
UHE-photons; universality; photons; gamma-rays; Pierre Auger Observatory; extensive air showers; shower depth; muonic content; Fisher test;
| Subcategory | Experimental Results |
|---|---|
| Collaboration | Auger |
