Radiation fields of disk, BLR and torus in quasars and blazars: Implications for γ-ray absorption

Alina C. Donea, R. J. Protheroe

Research output: Contribution to journalReview ArticleResearchpeer-review

101 Citations (Scopus)


The radiation fields external to the jets and originating from within a few parsecs from the black hole, are discussed in this paper. They are the direct radiation from an accretion disk in symbiosis with jets, the radiation field from the broad line region (BLR) surrounding the accretion disk, and the infrared radiation from a dusty torus. The jet/disk symbiosis modifies the energetics in the central parsec of active galactic nuclei (AGN) such that for a given accretion rate, a powerful jet would occur at the expense of the disk luminosity, and consequently the disk would less efficiently ionize the BLR clouds or heat the dust in the torus, thereby affecting potentially important target photon fields for interactions of γ-rays, accelerated electrons and protons along the jet. Motivated by unification schemes of AGN, we briefly review the evidence for the existence of BLRs and small-scale dust tori in BL Lacs and Fanaroff-Riley Class I (FR-I) radio galaxies. We propose that an existing jet-accretion disk symbiosis can be extrapolated to provide a large-scale symbiosis between other important dusty constituents of the blazar/FR-I family. In the present paper, we discuss in the context of this symbiosis interactions of GeV and TeV γ-rays produced in the jet with the various radiation fields external to the jet in quasars and blazars, taking account the anisotropy of the radiation.

Original languageEnglish
Pages (from-to)377-393
Number of pages17
JournalAstroparticle Physics
Issue number4
Publication statusPublished - 1 Jan 2003


  • γ-ray
  • Accretion disk
  • AGN
  • Broad line region
  • Photon-photon pair production
  • Torus

Cite this