2004ApJ...602..103F

The sizes of the broad-line regions (BLRs) in γ-ray active galactic nuclei (AGNs) are estimated from their optical continuum luminosity by using the empirical relation between R_BLRand L_λ,opt. Using broad emission line data, we derive the photon energy density in the relativistic blobs near the massive black holes in AGNs. We calculate the power of the broad-line photons Compton upscattered by the relativistic electrons in the blobs. Compared with observed γ-ray emission data, the Doppler factors δ of the blobs for a sample of 36 γ-ray AGNs are derived that are in the range of ∼3-17. We estimate the central black hole masses of these γ-ray AGNs from the sizes of the BLRs and the broad-line widths. It is found that the black hole masses are in the range of ∼10⁸-10¹⁰ M_☉. A significant correlation is found between the Doppler factor δ and the core dominance parameter R. The results are consistent with the external radiation Compton models for γ-ray emission from AGNs. The soft seed photons are probably from the BLRs.