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

PIERRE AUGER COLLABORATION (A. AAB, ... , A. MARIAZZI, ET AL)

ASTROPHYSICAL JOURNAL

IOP PUBLISHING LTD

Lugar: Londres; Año: 2015 vol. 802

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 atthe Pierre Auger Observatory including for the first time events with zenith anglebetween 60◦ and 80◦. We perform two Rayleigh analyses, one in the rightascension and one in the azimuth angle distributions, that are sensitive to modulationsin right ascension and declination, respectively. The largest departurefrom isotropy appears in the E > 8 EeV energy bin, with an amplitude for thefirst harmonic in right ascension rα1 = (4.4±1.0)×10−2, that has a chance probabilityP(≥ rα1 ) = 6.4×10−5, reinforcing the hint previously reported with verticalevents alone.