Propagation of Ultra High Energy Cosmic Rays in extra-galactic magnetic fierlds: simulations at the scrutiny of recent AUGER measurements

by Dr Dario Grasso (I.N.F.N. Pisa)

Monday 25 Feb 2008, 13:15 → 14:15 Europe/Stockholm

FA31

The results of AUGER, as well as of other extensive air showers experiments, proved that Ultra High Energy Cosmic Ryas (UHECRs) are mainly protons and/or composite nuclei. Those particles may undergo sizeable deflections in the intervening extra galactic magnetic fields (EGMFs). In last years it was hotly debated how large such deflections may be and if they could prevent the identification of UHECR sources. That was done by mean of numerical simulations of the evolution of EGMFs during structure formation. Different simulations, however, provided discordant results. I will show how the recent AUGER finding of a correlation between the arrival direction of most energetic UHECRs and the nearby AGNs/galaxy structures are compatible only with those simulations which predict weak EGMFs . While UHECR deflections in those weak fields may hardly be detectable, I will discuss how their imprint may still be found in the UHECR energy spectrum.