INVESTIGADORES
MOLLERACH Maria Silvia
artículos
Título:
Magnetic lensing of extremely high energy cosmic rays in a galactic wind
Autor/es:
D. HARARI, S. MOLLERACH Y E. ROULET.
Revista:
JOURNAL OF HIGH ENERGY PHYSICS
Editorial:
SPRINGER
Referencias:
Año: 2000 vol. 10 p. 1 - 13
ISSN:
1126-6708
Resumen:
We show that in the model of Galactic magnetic wind recently proposed to
explain the extremely high energy (EHE) cosmic rays so far observed as
originating from a single source (M87 in the Virgo cluster), the magnetic field
strongly magnifies the fluxes and produces multiple images of the source. The
apparent position on Earth of the principal image moves, for decreasing
energies, towards the galactic south. It is typically amplified by an order of
magnitude at $E/Z\sim 2\times 10^{20}$ eV, but becomes strongly demagnified
below $10^{20}$ eV. At energies below $E/Z\sim 1.3\times 10^{20}$ eV, all
events in the northern galactic hemisphere are due to secondary images, which
have huge amplifications ($>10^2$). This model would imply strong asymmetries
between the north and south galactic hemispheres, such as a (latitude
dependent) upper cut-off value below $2\times 10^{20}$ eV for CR protons
arriving to the south and lower fluxes in the south than in the north above
$10^{20}$ eV. The large resulting magnifications reduce the power requirements
on the source, but the model needs a significant tunning between the direction
to the source and the symmetry axis of the wind. If more modest magnetic field
strengths were assumed, a scenario in which the observed EHE events are heavier
nuclei whose flux is strongly lensed becomes also plausible and would predict
that a transition from a light composition to a heavier one could take place at
the highest energies.