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 angle 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 modulations in right ascension and declination, respectively. The largest departure from isotropy appears in the $Egt 8$ EeV energy bin, with an amplitude for the first harmonic in right ascension $r_{1}^{alpha }=(4.4pm 1.0) imes {{10}^{-2}}$, that has a chance probability $P(geqslant r_{1}^{alpha })=6.4 imes {{10}^{-5}}$, reinforcing the hint previously reported with vertical events alone.

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

VALORE, LAURA;GUARINO, FAUSTO;COLALILLO, ROBERTA;
2015

Abstract

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 angle 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 modulations in right ascension and declination, respectively. The largest departure from isotropy appears in the $Egt 8$ EeV energy bin, with an amplitude for the first harmonic in right ascension $r_{1}^{alpha }=(4.4pm 1.0) imes {{10}^{-2}}$, that has a chance probability $P(geqslant r_{1}^{alpha })=6.4 imes {{10}^{-5}}$, reinforcing the hint previously reported with vertical events alone.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11588/598568
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