Abstract
Blazars are powerful sources of high-energy (HE, ≳ 100 MeV) to very high-energy (VHE, ≳ 100
GeV) 𝛾-ray emissions. According to the unified scheme for radio-loud active galactic nuclei
(AGNs) radio galaxies are the parent class of the blazar population. Naturally one would expect
radio galaxies, as the parent population of blazars, to be intrinsic HE and possibly VHE 𝛾-ray
emitters. This was confirmed by recent VERITAS,MAGIC and HESS detections. Previous works
found that secondary electron/positron pairs can become efficiently isotropized by mild magnetic
fields in AGN environments, leading to off-axis HE–VHE 𝛾-ray cascades. We extend this work by
including a more realistic Shakura-Sunyaev (SS) accretion disk model, in addition to the isotropic
external radiation fields considered in previous works. We present the preliminary results of the
interplay between two external radiation fields, namely the broad-line region and UV emission
from the SS accretion disk, and then discuss future developments for this work.