Hidden Broad-line Regions in Seyfert 2 Galaxies: from the spectropolarimetric perspective

Abstract

The hidden broad-line regions (BLRs) in Seyfert 2 galaxies, which display broad emission lines (BELs) in their polarized spectra, are a key piece of evidence in support of the unified model for active galactic nuclei (AGNs). However, the detailed kinematics and geometry of hidden BLRs are still not fully understood. The virial factor obtained from reverberation mapping of type 1 AGNs may be a useful diagnostic of the nature of hidden BLRs in type 2 objects. In order to understand the hidden BLRs, we compile six type 2 objects from the literature with polarized BELs and dynamical measurements of black hole masses. All of them contain pseudobulges. We estimate their virial factors, and find the average value is 0.60 and the standard deviation is 0.69, which agree well with the value of type 1 AGNs with pseudobulges. This study demonstrates that (1) the geometry and kinematics of BLR are similar in type 1 and type 2 AGNs of the same bulge type (pseudobulges), and (2) the small values of virial factors in Seyfert 2 galaxies suggest that, similar to type 1 AGNs, BLRs tend to be very thick disks in type 2 objects.

6 pages, 2 figures, 2 tables, accepted for publication in The Astrophysical Journal Letters

References in corpus (10)

• A Catalog of Quasar Properties from SDSS DR7
• The black hole mass - stellar velocity dispersion relation of narrow-line Seyfert 1 galaxies
• Supermassive Black Holes with High Accretion Rates in Active Galactic Nuclei. IV. H$\beta$ Time Lags and Implications for Super-Eddington Accretion
• Supermassive Black Holes with High Accretion Rates in Active Galactic Nuclei. V. A New Size-Luminosity Scaling Relation for the Broad-Line Region
• The Black Hole Mass Scale of Classical and Pseudo Bulges in Active Galaxies
• The Correlation of Narrow Line Emission and X-ray Luminosity in Active Galactic Nuclei
• The Parsec-scale Accretion Disk in NGC 3393
• Upholding the Unified Model for Active Galactic Nuclei: VLT/FORS2 Spectropolarimetry of Seyfert 2 galaxies
• The location of the dust causing internal reddening of active galactic nuclei
• A Deep 0.3-10 keV Spectrum of the H${}_2$O Maser Galaxy IC 2560

Cited by in corpus (11)

• Supermassive Black Holes with High Accretion Rates in Active Galactic Nuclei. IX 10 New Observations of Reverberation Mapping and Shortened H$\beta$ Lags
• Monitoring AGNs with Hβ Asymmetry. I. First Results: Velocity-resolved Reverberation Mapping
• Failed radiatively Accelerated Dusty Outflow model of the Broad Line Region in Active Galactic Nuclei. I. Analytical solution
• The Black Hole Masses and Eddington Ratios of Type 2 Quasars
• Calibration of the virial factor $f$ in supermassive black hole masses of reverberation-mapped AGNs
• Reverberation mapping of narrow-line Seyfert 1 galaxy I Zwicky 1: black hole mass
• Detection of faint broad emission lines in type 2 AGN: III. On the $M_{BH}-{\sigma }_{\star }$ relation of type 2 AGN
• Dynamical evidence of the sub-parsec counter-rotating disc for a close binary of supermassive black holes in the nucleus of NGC 1068
• X-ray spectroscopy of the candidate AGN in Henize 2-10 and NGC 4178: Likely supernova remnants
• Measuring black hole mass of type I active galactic nuclei by spectropolarimetry
• Spectropolarimetric measurements of hidden broad lines in nearby megamaser galaxies: a lack of clear evidence for a correlation between black hole masses and virial products