Top: cosmic ray (solid lines), and photon (dashed lines) spectra (E² × dN/dE) compared to Auger spectrum for different models assuming a SFR source evolution: dip model, β = 2.5, E_max = 10^20.5 eV; late-transition model, β = 1.0, E_max = 10^20.5 eV and 10²¹ eV (short dashed lines); mixed composition, β = 2.1, E_max = 10²¹ eV; pure iron, β = 2.0, E_max = 10^20.5 eV. Bottom: integrated flux for the same models. Upper limits on the UHE photon flux from the Pierre Auger Observatory are also displayed (Abraham et al. 2008).