The dust sublimation radius as an outer envelope to the bulk of the narrow Fe Kalpha line emission in Type 1 AGN

Abstract

The Fe Kalpha emission line is the most ubiquitous feature in the X-ray spectra of active galactic nuclei (AGN), but the origin of its narrow core remains uncertain. Here, we investigate the connection between the sizes of the Fe core emission regions and the measured sizes of the dusty tori in 13 local Type 1 AGN. The observed Fe K emission radii (R_fe) are determined from spectrally resolved line widths in X-ray grating spectra, and the dust sublimation radii (R_dust) are measured either from optical/near-infrared reverberation time lags or from resolved near-infrared interferometric data. This direct comparison shows, on an object-by-object basis, that the dust sublimation radius forms an outer envelope to the bulk of the Fe K emission. R_fe matches R_dust well in the AGN with the best constrained line widths currently. In a significant fraction of objects without a clear narrow line core, R_fe is similar to, or smaller than the radius of the optical broad line region. These facts place important constraints on the torus geometries for our sample. Extended tori in which the solid angle of fluorescing gas peaks at well beyond the dust sublimation radius can be ruled out. We also test for luminosity scalings of R_fe, finding that Eddington ratio is not a prime driver in determining the line location in our sample. We discuss in detail potential caveats due to data analysis and instrumental limitations, simplistic line modeling, uncertain black hole masses, as well as sample selection, showing that none of these is likely to bias our core result. The calorimeter on board Astro-H will soon vastly increase the parameter space over which line measurements can be made, overcoming many of these limitations.

ApJ in press. Community comments greatly appreciated. 13 pages, 4 figures and 2 tables including an appendix

References in corpus (20)

• An XMM-Newton survey of broad iron lines in Seyfert galaxies
• Simultaneous X-ray/optical/UV snapshots of active galactic nuclei from XMM-Newton: spectral energy distributions for the reverberation mapped sample
• Reverberation Measurements of the Inner Radius of the Dust Torus in 17 Seyfert Galaxies
• The 2-79 keV X-ray Spectrum of the Circinus Galaxy with NuSTAR, XMM-Newton and Chandra: a Fully Compton-Thick AGN
• Parsec-scale dust distributions in Seyfert galaxies - Results of the MIDI AGN snapshot survey
• On the origin of the Fe K-alpha line cores in Active Galactic Nuclei
• The Broad-band X-ray Spectrum of IC 4329A from a Joint NuSTAR/Suzaku Observation
• NuSTAR unveils a Compton-thick Type 2 quasar in Mrk 34
• Luminosity and Redshift Dependence of the Covering Factor of AGNs viewed with WISE and SDSS
• The origin of ultra-fast outflows in AGN: Monte-Carlo simulations of the wind in PDS 456
• A dust-parallax distance of 19 megaparsecs to the supermassive black hole in NGC 4151
• A BLR origin for the iron K$\alpha$ line in NGC7213
• The Black Hole Mass of NGC 4151. II. Stellar Dynamical Measurement from Near-Infrared Integral Field Spectroscopy
• The ASTRO-H X-ray Astronomy Satellite
• The narrow Fe K$\alpha$ line and the molecular torus in active galactic nuclei - an IR/X-ray view
• A New Black Hole Mass Estimate for Obscured Active Galactic Nuclei
• The Seyfert 2 galaxy NGC 2110: hard X-ray emission observed by NuSTAR and variability of the iron K$\alpha$ line
• The broad-line region and dust torus size of the Seyfert 1 galaxy PGC50427
• A Compton thick AGN in the barred spiral NGC 4785
• Planet Formation Imager (PFI): Introduction and Technical Considerations

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