Kinematics of the broad-line emission gas in quasars and Seyfert nuclei - Line profiles in a gravitational model

Abstract

view Abstract Citations (29) References (23) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Kinematics of the broad-line emission gas in quasars and Seyfert nuclei - Line profiles in a gravitational model Carroll, T. J. ; Kwan, J. Abstract The parabolic-orbital model reported by Kwan and Carroll in 1982 for the broad emission-line regions of quasars and Seyfert galaxies is extended and improved to include the effects of a finite infalling cloud number and size. Disruption of the cloud by the differential angular momentum across its face results in a large velocity dispersion among the resulting fragment cloudlets. This velocity dispersion compensates for the small number of clouds at high velocity so that a fairly smooth profile is obtained. The drag of a confining intercloud wind is also considered. The major dynamical effect of this drag is to trap clouds with less than a certain angular momentum, l < 300 km s-1 x 50 pc for our standard model parameters. The trapping of clouds produces an asymmetry in the Lyα profile due to the absence of an outward leg for the trapped clouds. The asymmetry is reduced by the spiralling of the cloud material, and it shows up mainly in the core and far wings of the profile. The dependence of various line emissivities on the incident ionizing flux has been computed by Kwan in 1984. His results are convolved with the cloud velocity dispersions, and the resulting emission-line profiles demonstrate that the gravitational model can reproduce the observed broadness of He I λ5876 relative to Hβ (updated by Shuder in 1982). Profiles for Lyα, Mg II λ2798, C IV λ1549, and C III] λ1909 are also generated and compared to existing observations. Publication: The Astrophysical Journal Pub Date: January 1985 DOI: 10.1086/162765 Bibcode: 1985ApJ...288...73C Keywords: Astronomical Spectroscopy; Emission Spectra; Galactic Nuclei; Gravitational Effects; Kinematics; Quasars; Seyfert Galaxies; Astronomical Models; Clouds; Drag; Line Spectra; Astrophysics full text sources ADS |