Lightest Nuclei in UHECR versus Tau Neutrino Astronomy

Understand

UHECR may be either nucleons or nuclei; in the latter case the Lightest Nuclei, as He, Li, Be, explains at best the absence of Virgo signals and the crowding of events around Cen-A bent by galactic magnetic fields.

• This model fit the observed nuclear mass composition discovered in AUGER.
• However UHECR nucleons above GZK produce EeV neutrinos while Heavy Nuclei, as Fe UHECR do not produce much.
• UHECR He nuclei at few tens EeV suffer nuclear fragmentation (producing low energetic neutrino at tens PeVs) but it suffer anyway photo-pion GZK suppression (leading to EeV neutrinos) once above one-few 10^{20} eV.