Anisotropy studies with the Pierre Auger Observatory

TL;DR

This paper reports on the Pierre Auger Observatory's recent findings regarding the anisotropy in ultra-high energy cosmic ray arrival directions, including dipolar patterns, correlations with active galactic nuclei, and other extragalactic objects.

Contribution

It provides new measurements of anisotropy, updates on correlation searches with astrophysical sources, and explores anisotropies without relying on catalogs.

Findings

Detection of dipolar anisotropy at EeV energies

Correlations between >55 EeV cosmic rays and active galactic nuclei

Anisotropy signals found without using astronomical catalogs

Abstract

We report recent results from the Pierre Auger Observatory about the study of the anisotropy in the arrival directions of ultra-high energy cosmic rays. We present the results of the search for a dipolar anisotropy at the EeV energy scale. Measurements of the phase and the amplitude of the first harmonic modulation in the right-ascension distribution are discussed. For cosmic rays with energies above 55 EeV, we present an update of the search for correlations between their arrival directions and the positions of active galactic nuclei from the Veron-Cetty and Veron catalog. We also discuss the results of correlation analyses applied to other populations of extragalactic objects. Finally we present the search for anisotropies in the data without the usage of astronomical catalogues.