Magnetic lensing of extremely high energy cosmic rays in a galactic wind

We show that in the model of Galactic magnetic wind recently proposed to ex plain the extremely high energy (EHE) cosmic rays so far observed as origin ating from a single source (M87 in the Virgo cluster), the magnetic field s trongly magnifies the fluxes and produces multiple images of the source. Th e apparent position on Earth of the principal image moves, for decreasing e nergies, towards the galactic south. It is typically amplified by an order of magnitude at E/Z similar to 2 X 10(20) eV, but becomes strongly demagnif ied below 10(20) eV. At energies below E/Z similar to 1.3 X 10(20) eV, all events in the northern galactic hemisphere are due to secondary images, whi ch have huge amplifications (> 10(2)). This model would imply strong asymme tries between the north and south galactic hemispheres, such as a (latitude dependent) upper cut-off value below 2 X 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 fiel d strengths were assumed, a scenario in which the observed EHE events are h eavier nuclei whose flux is strongly lensed becomes also plausible and woul d predict that a transition from a light composition to a heavier one could take place at the highest energies.