Auger Test of the Cen A Model of Highest Energy Cosmic Rays

If, as recently proposed by Farrar and Piran, Cen A is the source of cosmic rays detected above the Greisen-Zatsepin-Kuz’min cutoff, neutrons are $\approx 140$ more probable than protons to be observed along its line of sight. This is because the proton flux is rendered nearly isotropic by $O\left(\mu \mathrm{G}\right)$ intergalactic magnetic fields. With the anticipated aperture of the Southern Auger Observatory, one may expect on the order of 2 neutron events $/$year above ${10}^{20}\mathrm{eV}$ in the line of sight of Cen A.