We have studied the Ly-al, Hbeta, Halpha and Mg II2798 line profiles of the Seyfert 1 galaxy III Zw 2. The shapes of these broad emission lines show evidence of a multicomponent origin and also features which may be identified as the peaks due to a rotating disk. We have proposed a two-component Broad Line Region (BLR) model consisting of an inner Keplerian relativistic disk and an outer structure surrounding the disk. The results of the fitting of the four Broad Emission Lines (BELs) here considered, are highly consistent in both the inner and outer component parameters. Adopting a mass of approx. 2 E8 sollar masses for the central object we found that the outer radius of the disk is approximately equal for the four considered lines (approx 0.01 pc). However, the inner radius of the disk is not the same: 0.0018 pc for Ly-alpha, 0.0027 pc for Mg II, and 0.0038 pc for the Balmer lines. This as well as the relatively broad component present in the blue wings of the narrow [OIII] lines indicate stratification in the emission-line region. Using long-term Hbeta observations (1972-1990, 1998) we found a flux variation of the BEL with respect to the [OIII] lines.Comment: ApJ, accepted, 22 pages, 10 figure
Abstract.We have studied the Balmer line shapes of NGC 3516 in order to find the structure of central Emission Line Region (ELR) and the physical parameters of the emitting plasma. The shapes of these broad emission lines show evidences of a multicomponent origin and also features which could be identified as the peaks of a rotating disc. We have proposed a two component Broad Line Region (BLR) model consisting of an inner Keplerian relativistic disc and an outer structure surrounding the disc which is composed by Broad Line and Narrow Line Regions (BLR and NLR). Adopting a mass of ∼4 × 10 7 M for the central object we found that the emitting disc is located from 0.004 pc to 0.018 pc. Using a well known method for laboratory plasma diagnostic, the Boltzmann plot, we estimated the electron temperature (≈12 500 K) and electron density (∼10 15 cm −3 ) of the disc and the surrounding region (T e ≈ 20 000 K and N e ∼ 10 15 cm −3 ).
Abstract.To investigate the structure of the Akn 120 emitting region we have analysed the spectral line profiles of Hα, H β , Lyα, C III [1909], C IV [1549] and Mg II [2798] lines using a Gaussian-decomposition approach. The decomposed shape of the Akn 120 lines indicates three separated broad line-emitting regions, in two of them, the systematic motions of emitting gas are present. It seems that one of the two regions has a high random velocity of emitters (≈2500 km s −1 ) and approaching line-of-sight velocities, and the other has a smaller random velocity of emitters (≈1000 km s −1 ) and receding line-of-sight velocities. Also, we discuss the long-term H β line shape variation in the spectra of Akn 120. The H β line (from 96 spectra) was fitted with three broad and one narrow Gaussians through the entire period considered (1977)(1978)(1979)(1980)(1981)(1982)(1983)(1984)(1985)(1986)(1987)(1988)(1989)(1990). The central broad as well as blue component of H β and shelf (Fe II template) cause the H β line shape variation. Besides the Gaussian decomposition of the shapes of the three hydrogen lines we propose here a disk model with two more regions located symmetrically to the disk plane. Using the fitting method with the disk model we obtained the parameters of the disk: i = 10• ; Rinn ≈ 120−200 Rg, Rout ≈ 1000 Rg.Key words. galaxies: individual (Arakelian 120) -galaxies: Seyfert -line: profiles -accretion, accretion disks IntroductionThe spectral line investigation of Active Galactic Nuclei (AGNs) helps us to understand physical properties and kinematics of emitting gas. The AGN radiation comes from a compact very luminous center of a galaxy, and in their spectra narrow and broad emission lines are observed. These lines come from a very extensive emitting line region, where plasma has very different parameters; the electron density can range from 10 2 cm −3 to 10 11 cm −3and electron temperatures from several hundreds to tens of thousands Kelvin (see e.g. Osterbrock 1990). It is widely accepted that the "central engine" consists of a massive black hole fueled by an accretion disk. Also, observations in a wide band of wavelengths (X, UV, optical) indicate that an accretion disk should be present as a central part of the majority of AGNs. Emission line profiles of Active Galactic Nuclei usually show variabilities. Investigations of these variations could provide information about the structure, size and kinematics of the emitting gas in the central part of these objects (see e.g. Foltz et al. 1983;Peterson et al. 1985Peterson et al. , 1989Peterson et al. , 1998Peterson & Gaskell 1991; Peterson 1993;Winge et al. Send offprint requests to: L.Č. Popović, e-mail: lpopovic@aob.bg.ac.yu 1996; Wandel et al. 1999, etc.). According to the standard model, the broad emission lines observed in spectra of AGNs originate in the high-velocity gas of the surrounding Broad Line Region (BLR) ionized by the UV and optical radiation of the compact central source. Fluctuation in the ionizing continuum cause the variations in emissio...
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