Gamma rays precursors and afterglows surrounding UHECR events: Z-burst model is still alive

Abstract

The Z-burst model and the direct propagation of UHE proton in negligible extragalactic magnetic fields produce gamma-rays afterglows and precursors halos, respectively at GeVs and TeV energy band a few degree around the UHECR arrival direction. The possible correlation of UHECR clusters (doublet, triplet) with nearby BL Lac sources at E_p = 4*10^19 eV offer a test for this necessary Gamma-UHECR trace. We estimate the secondary gamma energy and spectra and we suggest how to disentangle between the different scenarios. We show why Z-Burst model is still the most realistic model to explain UHECR behaviour and their correlation to known BL Lac sources.

Comments: 8 pages, 1 Figure, Cris Conference 2004 (submitted to Nuclear Phys B)