a1, a2: dependence on the accretion rate, Ṁ = 0.01 (red, dotted), 0.1 (green, dashed), and 1.0 (blue, solid). (a1) log T_p as a function of log r and (a2) log νL_ν with log ν. (b1, b2) Dependence on mass of BH, M_BH = 10² (blue, solid), 10⁴ (green, dashed), 10⁶ (red, dotted) in the production of γ rays. (b1) log T_p as a function of log r and in (b2) the corresponding spectra are plotted. The gamma ray emission is presented in grey.