Black Hole Masses and Doppler Factors of Gamma-Ray Active Galactic Nuclei

• Published in: The Astrophysical journal Vol. 602; no. 1; pp. 103 - 110
• Main Authors: Fan, Zhong-Hui, Cao, Xinwu
• Format: Journal Article
• Language: English
• Published: IOP Publishing 10.02.2004
• ISSN: 0004-637X; 1538-4357
• DOI: 10.1086/380902

The sizes of the broad-line regions (BLRs) in gamma-ray active galactic nuclei (AGNs) are estimated from their optical continuum luminosity by using the empirical relation between R[sub]BLR and L[sub]lambda,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 gamma-ray emission data, the Doppler factors delta of the blobs for a sample of 36 gamma-ray AGNs are derived that are in the range of [approx]3-17. We estimate the central black hole masses of these gamma-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 [approx]10[super]8-10[super]10 M[sub]o. A significant correlation is found between the Doppler factor delta and the core dominance parameter R. The results are consistent with the external radiation Compton models for gamma-ray emission from AGNs. The soft seed photons are probably from the BLRs.