Black hole masses and Doppler factors of gamma-ray active galactic nuclei.
FAN Z.-H. and CAO X.
Abstract (from CDS):
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 RBLRand Lλ,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 ∼108-1010M☉. 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.
Black Hole Physics - Galaxies: Active - Gamma Rays: Theory - Radiation Mechanisms: Nonthermal