Highlights from the Pierre Auger Observatory

TL;DR

This paper summarizes key findings from the Pierre Auger Observatory, including updates on cosmic ray energy spectrum, composition, arrival directions, and new measurements of atmospheric phenomena and particle interactions.

Contribution

It provides new measurements of the energy spectrum, X_max distributions, and p-air cross section, expanding the observatory's astrophysics and particle physics insights.

Findings

First measurements of the energy spectrum down to 3 x 10^{17} eV

Distribution of the shower maximum, X_max, presented for the first time

First measurement of the p-air cross section at ~ 10^{18} eV

Abstract

This paper summarizes some highlights from the Pierre Auger Observatory that were presented at the ICRC 2011 in Beijing. The cumulative exposure has grown by more than 60% since the previous ICRC to above 21000 km^2 sr yr. Besides giving important updates on the energy spectrum, mass composition, arrival directions, and photon- and neutrino upper limits, we present first measurements of the energy spectrum down to 3 x 10^{17} eV, first distributions of the shower maximum, X_max, together with new surface detector related observables sensitive to X_max, and we present first measurements of the p-air cross section at ~ 10^{18} eV. Serendipity observations such as of atmospheric phenomena showing time evolutions of elves extend the breadth of the astrophysics research program.