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by Fermi with 5-year survey, by their soft nonthermal emission from nonthermal electrons in coronae of ac- cretion disks, giving an interesting test for our model. We estimated the > 100 MeV gamma-ray flux from the observed hard X-ray flux of NGC 4151 (the bright- est Seyfert galaxy in all sky [35]) using the ITU08 model [26]. Then, NGC 4151 is marginally detectable when Γ = 3 . 8, and easily detectable with Γ = 3 . 5 with one year survey sensitivity. 

The right panel of Figure 4 shows the differential flux distribution of gamma-ray blazars and non-blazar AGNs multiplied by flux, showing the contribution to the EGRB per unit logarithmic flux interval. EGRB from blazars should practically be resolved into dis- crete sources. We find that the fraction of EGRB flux that should be resolved is 98% against the to- tal blazar EGRB flux in 5-year survey. On the other hand, EGRB from non-blazar AGNs is hardly resolved into discrete sources by Fermi . The predicted fraction of non-blazar EGRB flux resolved by Fermi is ∼ 0.01 % with 5-year survey, respectively, against the total non- blazar EGRB flux. These results are in sharp contrast to those for blazars, although the contributions to the total EGRB by the two populations are comparable at around 100 MeV. 

The above results mean that a considerable part of EGRB at around 100 MeV will remain unresolved even with the Fermi sensitivity, because there is a considerable contribution from non-blazar AGNs to EGRB at ∼ 100 MeV. However, the contribution from non-blazars should rapidly decrease with increasing photon energy, and almost all of the total EGRB flux at > ∼ 1 GeV should be resolved into discrete blazars by Fermi , if there is no significant source contribut- ing to EGRB other than blazars. It should be noted that these predictions can be tested by Fermi rela- tively easily, without follow-up or cross check at other wavebands, once measurements of source counts and 

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EGRB flux have been done by the Fermi data. There- fore this gives a simple and clear test for our theoret- ical model [26]. 

Since Fermi is the most sensitive GeV gamma-ray observatory to date, it has the potential to discover many new high-redshift blazars. GeV photons from high-redshift sources are expected to suffer intergalac- tic absorption due to e ± pair production interactions with the cosmic UV background radiation. The result- ing features in the spectra of such blazars could there- fore be a key probe of the poorly-understood UV back- ground radiation and provide valuable insight into the cosmic dark ages [50–52]. 

## B. High Redshift Fermi Blazars 

