IFLP   13074
INSTITUTO DE FISICA LA PLATA
Unidad Ejecutora - UE
artículos
Título:
Correlation of the highest-energy cosmic rays with the positions of nearby active galactic nuclei
Autor/es:
PIERRE AUGER COLLABORATION (J. ABRAHAM, ... , A. MARIAZZI, ET AL)
Revista:
ASTROPARTICLE PHYSICS
Editorial:
Elsevier
Referencias:
Lugar: Amsterdam (Holanda); Año: 2007
ISSN:
0927-6505
Resumen:
Data collected by the Pierre Auger Observatory provide evidence for
anisotropy in the arrival directions of the cosmic rays with the highest
energies, which are correlated with the positions of relatively nearby active
galactic nuclei (AGN) \cite{science}. The correlation has maximum significance
for cosmic rays with energy greater than ~ 6x10^{19}$ eV and AGN at a distance
less than ~ 75 Mpc. We have confirmed the anisotropy at a confidence level of
more than 99% through a test with parameters specified {\em a priori}, using an
independent data set. The observed correlation is compatible with the
hypothesis that cosmic rays with the highest energies originate from
extra-galactic sources close enough so that their flux is not significantly
attenuated by interaction with the cosmic background radiation (the
Greisen-Zatsepin-Kuz'min effect). The angular scale of the correlation observed
is a few degrees, which suggests a predominantly light composition unless the
magnetic fields are very weak outside the thin disk of our galaxy. Our present
data do not identify AGN as the sources of cosmic rays unambiguously, and other
candidate sources which are distributed as nearby AGN are not ruled out. We
discuss the prospect of unequivocal identification of individual sources of the
highest-energy cosmic rays within a few years of continued operation of the
Pierre Auger Observatory.