Extra-galactic sources.

The diffuse fluxes of neutrinos coming from AGNs have been calculated by several authors~[#stecker##1#,#nellen##1#,#szabo##1#,#mannheim##1#,#protheroe##1#]. Other calculations give the neutrino flux of neutrinos originated by the destructions of topological defects~[#bhs##1#,#sigl##1#] (TD). The predictions from ref.~[#szabo##1#] and the most optimistic flux prediction from ref.~[#bhs##1#] are in contradiction with the measurements made in the Fréjus experiment~[#frejus##1#]. Therefore they are not considered here. Figure~#fgflux#258> shows the variations of the different neutrino fluxes which are compared with the flux of atmospheric neutrinos~[#volkova##1#].

#figure260#
Figure: Neutrino fluxes as function of the neutrino energy for different models: SDSS, NMB (continuous lines), MRLA, MRLB (dashed line), PRO (dotted line), BHSl, BHSh and SIG (dash-dotted lines). The lower continuous lines correspond to the calculation for atmospheric neutrinos. The black region is for different zenital angles. The fluxes have been multiplied by the neutrino energy.

The rates of upward muons induced by AGN neutrinos and by neutrinos from TD in a 1km#tex2html_wrap_inline720# detector have been calculated by taking into account of the different neutrino fluxes and of the attenuation of neutrinos by the Earth and are compared to what expected from atmospheric neutrinos. Table~#lmtbtab4#266> shows that the event rates for cosmic neutrinos decrease with the increasing energy threshold more slowly than the rate of events due to atmospheric neutrinos. The rates obtained by using the neutrino fluxes of ref.~[#stecker##1#,#nellen##1#] for AGNs and of ref.~[#volkova##1#] for atmospheric neutrinos with energy threshold of 1 and 10TeV are in good agrement with the calculations reported in ref.~[#gandhi##1#].

#table270#
Table: Number of upward-going induced muons expected per year in a km#tex2html_wrap_inline722# detector for different models.