Astropart. Phys., submitted

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


Alina-C. Donea¹ and R.J. Protheroe
Department of Physics and Mathematical Physics
The University of Adelaide, Adelaide, SA 5005, Australia

Abstract:

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 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 BRL clouds or heat the dust in the torus, thereby affecting potentially important target photon fields for interactions of gamma-rays, accelerated electrons and protons along the jet.

Motivated by unification schemes of active galactic nuclei, we briefly review the evidence for the existence of broad line regions 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 gamma-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.

PACS Codes:

98.54.Aj Quasars

98.54.Cm Active and peculiar galaxies

98.70.Rz gamma-ray sources

Keywords:

accretion disk, broad line region, torus, gamma-ray, AGN, photon-photon pair production