Contribution of the disk emission to the broad emission lines in AGNs: Two-component model^*

¹ Astronomical Observatory, Volgina 7, 11160 Belgrade, Serbia e-mail: [lpopovic;ebon]@aob.bg.ac.yu
² Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany (Alexander von Humboldt fellow) e-mail: lpopovic@aip.de
³ Isaac Newton Institute of Chile, Yugoslavia Branch, Yugoslavia
⁴ Instituto de Astrofísica de Canarias C/ Vía Làctea, s/n 38200 La Laguna, Tenerife, Spain e-mail: emg@ll.iac.es
⁵ Department of Astronomy, Faculty of Mathematics, University of Belgrade, Studentski trg 16, 11000 Belgrade, Serbia e-mail: dilic@matf.bg.ac.yu

Received: 2 October 2003
Accepted: 3 May 2004

Abstract

We present an investigation of the structure of the emission line region in a sample of 12 single-peaked Active Galactic Nuclei (AGNs). Using the high resolution Hβ and Hα line profiles observed with the Isaac Newton Telescope (La Palma) we study the substructure in the lines (such as shoulders or bumps) which can indicate a disk or disk-like emission in Broad Line Regions (BLRs). Applying Gaussian analysis we found that both kinds of emission regions, BLR and NLR, are complex. In this sample the narrow [OIII] lines are composites of two components; NLR1 which have random velocities from ~200 to 500 km s^-1 and systematic velocities toward the blue from 20 to 350 km s^-1, and NLR2 with smaller random velocities (~100-200 km s^-1) and a redshift corresponding to the cosmological one. The BLR also have complex structure and we apply a two-component model assuming that the line wings originate in a very broad line region (VBLR) and the line core in an intermediate line region (ILR). The VBLR is assumed to be an accretion disk and the ILR a spherical emission region. The model fits very well the Hα and Hβ line profiles of the AGNs.