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Astron. Astrophys. 352, 32-38 (1999)

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Basic properties of gamma-ray loud blazars

K.S. Cheng 1, J.H. Fan 2 and L. Zhang 1,3

1 Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong, P.R. China
2 Center for Astrophysics, Guangzhou Normal University, Guangzhou 510400, P.R. China
3 Department of Physics, Yunnan University, Kunming, P.R. China

Received 22 January 1999 / Accepted 12 October 1999


In this paper, a method is proposed to determine the basic properties of [FORMULA]-ray loud blazars, among them the central black hole mass, M, the Doppler factor, [FORMULA], the propagation angle of the [FORMULA]-rays with respect to the symmetric axis of a two-temperature accretion disk, [FORMULA], and the distance (i.e. the height above the accretion disk), d at which the [FORMULA]-rays are created, for seven [FORMULA]-ray loud blazars with available GeV variability timescales and in which the absorption effect of a [FORMULA]-ray and the beaming effect have been taken into account. Our results indicate that, if we take the intrinsic [FORMULA]-ray luminosity to be [FORMULA] times the Eddington luminosity, [FORMULA], the masses of the blazars are in the range of [FORMULA] ([FORMULA]) or [FORMULA] ([FORMULA]), the Doppler factors ([FORMULA]) lie in the range of 0.57 to 3.72 ([FORMULA]) or 0.79 to 5.33 ([FORMULA]), the angle ([FORMULA]) is in the range of [FORMULA] to 43o ([FORMULA]) or [FORMULA] to 39o ([FORMULA]), and the distance (d) is in the range of 28[FORMULA] to 411[FORMULA] ([FORMULA]) or 26[FORMULA] to 366[FORMULA] ([FORMULA]). For 3C279, the case of a uniformly-bright disk is also adopted to determine the basic parameters, which are compared with those obtained for a two-temperature disk as well as those obtained by Becker & Kafatos (1995). Our model results are independent of [FORMULA]-ray emission mechanisms but they do depend on the X-ray emission mechanism of the accretion disk.

Key words: galaxies: BL Lacertae objects: general – galaxies: jets – galaxies: quasars: general – gamma rays: observations

© European Southern Observatory (ESO) 1999

Online publication: November 23, 1999