INVESTIGADORES
MOLLERACH Maria Silvia
artículos
Título:
Bounds on the density of sources of ultra-high energy cosmic rays from the Pierre Auger Observatory
Autor/es:
THE PIERRE AUGER COLLABORATION, INCLUYE S. MOLLERACH
Revista:
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
Editorial:
IOP PUBLISHING LTD
Referencias:
Lugar: Londres; Año: 2013
ISSN:
1475-7516
Resumen:
We discuss the effects of diffusion of high energy cosmic rays in
turbulent extra-galactic magnetic fields. We find an approximate
expression for the low energy suppression of the spectrum of the
different mass components (with charge Z) in the case in which this
suppression happens at energies below ~ Z EeV, so that energy losses are
dominated by the adiabatic ones. The low energy suppression appears when
cosmic rays from the closest sources take a time comparable to the age
of the Universe to reach the Earth. This occurs for energies E < Z
EeV (B/nG)&surd;(lc/Mpc)(ds/70Mpc) in terms of the
magnetic field RMS strength B, its coherence length lc and
the typical separation between sources ds. We apply this to
scenarios in which the sources produce a mixed composition and have a
relatively low maximum rigidity (Emax ~ (2-10)Z EeV),
finding that diffusion has a significant effect on the resulting
spectrum, the average mass and on its spread, in particular reducing
this last one. For reasonable values of B and lc these
effects can help to reproduce the composition trends observed by the
Auger Collaboration for source spectra compatible with Fermi
acceleration.