Angel Albarracín - Academia.edu (original) (raw)

Papers by Angel Albarracín

Astrophysical observations of ultra-high-energy cosmic rays with the Pierre Auger Observatory

Studies of the cosmic ray energy spectrum at the highest energies with the Pierre Auger Observatory.

Astroparticle Physics, 2010

Physical Review Letters, 2008

$Research paper thumbnail of An upper limit to the photon fraction in cosmic rays above 10 19 eV from the Pierre Auger Observatory$

Astroparticle Physics, 2007

Astroparticle Physics, 2008

Journal of Cosmology and Astroparticle Physics, 2012

Science, 2007

Using data collected at the Pierre Auger Observatory during the past 3.7 years, we demonstrated a... more Using data collected at the Pierre Auger Observatory during the past 3.7 years, we demonstrated a correlation between the arrival directions of cosmic rays with energy above ~ 6x10^{19} electron volts and the positions of active galactic nuclei (AGN) lying within ~ 75 megaparsecs. We rejected the hypothesis of an isotropic distribution of these cosmic rays with at least a 99% confidence level from a prescribed a priori test. The correlation we observed is compatible with the hypothesis that the highest energy particles originate from nearby extragalactic sources whose flux has not been substantially reduced by interaction with the cosmic background radiation. AGN or objects having a similar spatial distribution are possible sources.