Speaker
Description
The presence of an accretion disk (AD) in active galactic nuclei (AGN) has limited and indirect observational support. In order to evaluate the extent to which the AD is a source of the broad Balmer lines and high ionization UV lines in radio-loud (RL) AGN, we focused on an extremely jetted RL quasar 3C 47 at z = 0.425, that shows a double-peaked profile. The work presents its new optical spectra from CAHA and UV observations from the HST/FOS covering the rest-frame spectral range from 2000 to 7000A and addresses the question of whether the AD can account for the observed profile. A relativistic Keplerian accretion disk model, a Bayesian approach, and a multicomponent non-linear fitting were utilized. In addition to the low ionization lines (Hbeta, Halpha, and MgII), the profile of the prototypical high ionization lines (HILs) is also modeled by the contribution of the AD, with additional components due to outflows and emissions from the innermost part of the narrow line regions (NLRs). The model successfully explained the observed profiles of Hbeta, Halpha and MgII. The profile of the HILs is also modeled by the contribution of the AD, along with fairly symmetric additional components (a failed wind scenario) and emissions from the innermost part of the NLRs. The disk parameters, such as inner and outer radii, inclination to the line of sight, emissivity index, and local broadening parameters are determined. The agreement between the observed profile and the model is remarkable and the work provides convincing direct observational evidence for the presence of an AD and the findings support the notion that the double-peaked profiles originate from the AD surrounding a SMBH. The main alternative, a double BLR associated with a binary black hole is found to be less appealing than the disk model for the quasar 3C 47.
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