Emission Line Properties of Seyfert Galaxies in the 12 Micron Sample

Abstract

We present spectroscopy of emission lines for 81 Seyfert 1 and 104 Seyfert 2 galaxies in the IRAS 12$\mu$m galaxy sample. We analyzed the emission-line luminosity functions, reddening, and other gas diagnostics. The narrow-line regions (NLR) of Sy1 and 2 galaxies do not significantly differ from each other in most of these diagnostics. Combining the H$\alpha$/H$\beta$ ratio with a new reddening indicator-the [SII]6720/[OII]3727 ratio, we find the average $E(B-V)=0.49\pm 0.35$ for Sy1s and $0.52\pm 0.26$ for Sy2s. The NLR of Sy1 galaxies has only marginally higher ionization than the Sy2s. Our sample includes 22 Sy1.9s and 1.8s. In their narrow lines, these low-luminosity Seyferts are more similar to the Sy2s than the Sy1s. We construct a BPT diagram, and include the Sy1.8s and 1.9s. They overlap the region occupied by the Sy2s. The C IV equivalent width correlates more strongly with [O III]/H$\beta$ than with UV luminosity. The Sy1 and Sy2 luminosity functions of [OII]3727 and [OIII]5007 are indistinguishable. Unlike the LF's of Seyfert galaxies measured by SDSS, ours are nearly flat at low L. The larger number of faint Sloan "AGN" is attributable to their inclusion of weakly emitting LINERs and H II+AGN "composite" nuclei, which do not meet our classification criteria for Seyferts. An Appendix investigates which emission line luminosities provide the most reliable measures of the total non-stellar luminosity. The hard X-ray or near-ultraviolet continuum luminosity can be crudely predicted from either the [O III]5007 luminosity, or the combination of [O III]+H$\beta$, or [N II]+H$\alpha$ lines, with a scatter of $\pm 4$ times for the Sy1s and $\pm 10$ times for the Sy2s. The latter two hybrid (NLR+BLR) indicators have the advantage of predicting the same HX luminosity independent of Seyfert type.

arXiv comment70 pages, including 15 Figures and 10 Tables. Accepted for publication in The Astrophysical Journal

References in corpus (42)

• The Host Galaxies of AGN
• Theoretical Modeling of Starburst Galaxies
• A Search for "Dwarf" Seyfert Nuclei. III. Spectroscopic Parameters and Properties of the Host Galaxies
• Linear Regression for Astronomical Data with Measurement Errors and Intrinsic Scatter
• A Hubble Space Telescope Imaging Survey of Nearby Active Glactic Nuclei
• A Search for "Dwarf" Seyfert Nuclei. IV. Nuclei with Broad H-alpha Emission
• Optical Spectroscopy of the IRAS 1-Jy Sample of Ultraluminous Infrared Galaxies
• An XMM-Newton spectral survey of 12 micron selected galaxies. I. X-ray data
• The Extended 12 Micron Galaxy Sample
• Dusty, Radiation Pressure Dominated Photoionization. I. Model Description, Structure And Grids
• The Relationship of Hard X-ray and Optical Line Emission in Low Redshift Active Galactic Nuclei
• Emission-line Diagnostics of Low Metallicity AGN
• The luminosity dependence of the Type 1 AGN fraction
• Nuclear Luminosities and Radio Loudness of Seyfert Nuclei
• Accretion and star formation rates in low redshift type-II active galactic nuclei
• Optical Spectral Signatures of Dusty Starburst Galaxies
• Active Galactic Nuclei in the Sloan Digital Sky Survey: II. Emission-Line Luminosity Function
• Are the Narrow Line Regions in Active Galaxies Dusty and Radiation Pressure Dominated?
• Radio Loud and Radio Quiet Active Galactic Nuclei
• A multi-wavelength study of the Seyfert 1 galaxy MCG-6-30-15
• Spitzer-IRS high resolution spectroscopic survey of the 12 micron Seyfert galaxies: II. Results for the Complete Dataset
• The Correlation of Narrow Line Emission and X-ray Luminosity in Active Galactic Nuclei
• Type 1 AGN at low z. II. The relative strength of narrow lines and the nature of intermediate type AGN
• On the origin of the C IV Baldwin effect in AGN
• An XMM-Newton spectral survey of 12 micron selected galaxies. II. Implications for AGN selection and unification
• Luminosity and Redshift Dependence of the Covering Factor of AGNs viewed with WISE and SDSS
• The [OIII] emission line luminosity function of optically selected type-2 AGN from zCOSMOS
• Large-Scale Outflows in Edge-on Seyfert Galaxies. I. Optical Emission- Line Imaging and Optical Spectroscopy
• Broad Hbeta Emission-Line Variability in a Sample of 102 Local Active Galaxies
• Integral Field Near-IR Spectroscopy of a Sample of Seyfert and LINER Galaxies I: The Data
• High-ionization mid-infrared lines as black hole mass and bolometric luminosity indicators in active galactic nuclei
• Type 1 AGN at low z. III. The optical narrow line ratios
• STIS ultraviolet/optical spectroscopy of `warm' ultraluminous infrared galaxies
• Emission Line-Ultraviolet to X-Ray Continuum Correlations: Constraints on the Anisotropy of the Ionizing Continuum in Active Galactic Nuclei
• The broad-band XMM-Newton and INTEGRAL spectra of bright type 1 Seyfert galaxies
• Spectral Evolution in High Redshift Quasars from the Final BOSS Sample
• Seyfert-Type Dependences of Narrow Emission-Line Ratios and Physical Properties of High-Ionization Nuclear Emission-Line Regions in Seyfert Galaxies
• Infrared Luminosity Functions of AKARI-SDSS Galaxies
• UV Spectropolarimetry of Narrow-line Radio Galaxies
• BAT AGN Spectroscopic Survey-III. An observed link between AGN Eddington ratio and narrow emission line ratios
• The difference between the narrow line region of Seyfert 1 and Seyfert 2 galaxies
• Hα Imaging of Nearby Seyfert Host Galaxies

Cited by in corpus (25)

• The variable and non-variable X-ray absorbers in Compton-thin type-II Active Galactic Nuclei
• Calibration and Limitations of the Mg II line-based Black Hole Masses
• Assessing the sources of reionisation: a spectroscopic case study of a 30$\times$ lensed galaxy at $z\sim 5$ with Lyα, CIV, MgII, and [NeIII]
• Optical and mid-infrared line emission in nearby Seyfert galaxies
• A Radio Polarimetric Study to Disentangle AGN Activity and Star-Formation in Seyfert Galaxies
• Coronal Line Forest AGN I: physical properties of the emission-line regions
• Probing the nature and origin of dust in the reddened quasar IC 4329A with global modelling from X-ray to infrared
• NuSTAR Observations of AGN with Low Observed X-ray to [OIII] Luminosity Ratios: Heavily Obscured AGN or Turned-Off AGN?
• The molecular gas properties in local Seyfert 2 galaxies
• The high-ionization IR fine-structure lines as bolometric indicators of the AGN power: study of the complete 12 micron AGN sample
• Measuring chemical abundances in AGN from infrared nebular lines: HII-CHI-Mistry-IR for AGN
• Exploring the spectral variability of the Seyfert 1.5 galaxy Markarian 530 with Suzaku
• A More Efficient Search for H2O Megamaser Galaxies : The Power of the X-ray and Mid-infrared Photometry
• Polar Dust Emission in Quasar IR SEDs and Its Correlation with Narrow Line Regions
• Multi-line assessment of narrow-line regions in $z\sim$ 3 radio galaxies
• AstroSat/UVIT observations of IC4329A: Constraining the accretion disc inner radius
• $Herschel$/PACS OH Spectroscopy of Seyfert, LINER, and Starburst Galaxies
• Magnetic Fields, Star Formation Rates and Gas Densities at Sub-kpc Scales in a Pilot Sample of Nearby Galaxies
• The Collisional and Photoionized Plasma in the Polarized NLS1 galaxy Mrk 1239
• BASS. XLIX. Characterization of highly luminous and obscured AGNs: local X-ray and [NeV]$\lambda$3426 emission in comparison with the high-redshift Universe
• An observational link between AGN Eddington ratio and [NII]λ6583/Ha at 0.6<z<1.7
• A population of Optically Quiescent Quasars from WISE and SDSS
• Spatially Resolved Spectroscopic Study of nearby Seyfert Galaxies: Implications for a Population of "Missed" Seyferts at High-$\text{z}$
• DEIMOS Observations of WISE-Selected, Optically Obscured AGNs
• Physical Drivers of Emission Line Diversity of SDSS Seyfert 2s and LINERs After Removal of Contributions by Star Formation