Large scale distribution of ultra high energy cosmic rays detected at the Pierre Auger Observatory with zenith angles up to 80◦

AUGER COLLABORATION (VER F. SANCHEZ EN PUBL. ADJUNTA)

ASTROPHYSICAL JOURNAL

IOP PUBLISHING LTD

Lugar: Londres; Año: 2014

0004-637X

We present the results of an analysis of the large angular scale distribution of the arrival directions of cosmic rays with energy above 4 EeV detected at the Pierre Auger Observatory including for the first time events with zenith an- gle between 60◦ and 80◦. We perform two Rayleigh analyses, one in the right ascension and one in the azimuth angle distributions, that are sensitive to mod- ulations in right ascension and declination, respectively. The largest departure from isotropy appears in the E > 8 EeV energy bin, with an amplitude for the first harmonic in right ascension r1α = (4.4±1.0)×10−2, that has a chance proba- bility P(≥ r1α) = 6.4×10−5, reinforcing the hint previously reported with vertical events alone.