Ultrahigh Energy Neutrinos at the Pierre Auger Observatory
Figure 11
Thick lines represent differential and integrated upper limits (at C.L.) to the diffuse flux of UHE neutrinos (single flavour assuming equipartition) from the Pierre Auger Observatory for downward-going (equivalent search period = 2 yr of full Auger) and Earth-skimming (equivalent search period = 3.5 yr of full Auger). Limits from other experiments are also plotted [46–48]. All limits have been scaled to single flavour. The IceCube differential limit is scaled by a factor due to the different binning in energy with respect to the Auger differential limits. Thin lines: Expected fluxes for three theoretical models of cosmogenic neutrinos (scaled to single flavour when necessary). “p, Fermi-LAT” [43] corresponds to the best fit to UHECR spectrum incorporating the Fermi-LAT bound assuming that the transition from Galactic to extragalactic CRs takes place at eV. “p, evol-FRII” [12] assumes the FRII strong source evolution with a pure proton composition, dip transition model and maximum energy of UHECRs at the sources eV. “Fe, uniform” [12] represents an extreme model assuming an iron rich composition, low , uniform evolution of the UHECR sources.
