Orateur
Mlle
Roberta Colalillo
(INFN Napoli)
Description
The Pierre Auger Observatory, located near Malargue, Argentina, is the world largest
Ultra High Energy Cosmic Ray Observatory. It has been operating since 2004 and its
exposure reached almost 60 000 km2 sr yr, providing an unprecedented large and high
quality data set that have dramatically advanced our understanding of ultra-high
energy cosmic rays. The suppression of the flux around 5×10^19 eV is now confirmed without any doubt. Costraints on models of origin and propagation of cosmic rays have been placed from a combined fit of both flux and composition; moreover,
“top-down” source processes were disfavoured by strong limits placed on photon and
neutrino fluxes. From studies on the depth of shower maximum, a gradual shift to a
heavier composition from 3×10^18 eV was observed. More information on the
composition, on the fraction of primary protons, and on hadronic interactions at the
highest energies would be crucial to discriminate among the model classes of origin
and propagation of cosmic rays and to understand the cause of the observed flux
suppression. The Observatory is starting a major upgrade, named AugerPrime, to
address these goals: the upgrade will be presented and the expected performances
will be discussed.
Author
Mlle
Roberta Colalillo
(INFN Napoli)
