Localizing narrow Fe K$\alpha$ emission within bright AGN

Abstract

The 6.4 keV Fe Ka emission line is a ubiquitous feature in X-ray spectra of AGN, and its properties track the interaction between the variable primary X-ray continuum and the surrounding structure from which it arises. We clarify the nature and origin of the narrow Fe Ka emission using X-ray spectral, timing, and imaging constraints, plus possible correlations to AGN and host galaxy properties, for 38 bright nearby AGN ($z<0.5$) from the BAT AGN Spectroscopic Survey. Modeling Chandra and XMM-Newton spectra, we computed line full-width half-maxima (FWHMs) and constructed Fe Ka line and 2-10 keV continuum light curves. The FWHM provides one estimate of the Fe Ka emitting region size, RFeKa, assuming virial motion. A second estimate comes from comparing the degree of correlation between the variability of the continuum and line-only light curves, compared to simulated light curves. Finally, we extracted Chandra radial profiles to place upper limits on RFeKa. We found that for 90% (21/24) of AGN with FWHM measurements, RFeKa is smaller than the fiducial dust sublimation radius, Rsub. Despite a wide range of variability properties, the constraints on the Fe Ka photon reprocessor size independently confirm that RFeKa is smaller than Rsub in 83% of AGN. Finally, the imaging analysis yields loose upper limits for all but two sources; notably, the Circinus Galaxy and NGC 1068 show significant but subdominant extended Fe Ka emission out to $\sim$100 and $\sim$800 pc, respectively. Based on independent constraints, we conclude that the majority of the narrow Fe Ka emission in typical AGN predominantly arises from regions smaller than and presumably inside Rsub, and thus it is associated either with the outer broad line region or outer accretion disk. However, the large diversity of continuum and narrow Fe Ka variability properties are not easily accommodated by a universal scenario.

Accepted for publication in Astronomy and Astrophysics (A&A), 35 pages, 22 figures, 3 tables

References in corpus (39)

• HI4PI: A full-sky HI survey based on EBHIS and GASS
• Some Aspects of Measurement Error in Linear Regression of Astronomical Data
• Modeling the Time Variability of SDSS Stripe 82 Quasars as a Damped Random Walk
• BAT AGN Spectroscopic Survey - V. X-ray properties of the Swift/BAT 70-month AGN catalog
• X-ray reverberation around accreting black holes
• The XMM-Newton serendipitous survey IX. The fourth XMM-Newton serendipitous source catalogue
• The close environments of accreting massive black holes are shaped by radiative feedback
• BAT AGN Spectroscopic Survey I: Spectral Measurements, Derived Quantities, and AGN Demographics
• Occultation measurement of the size of the X-ray emitting region in the Active Galactic Nucleus of NGC 1365
• The innermost region of AGN tori: implications from the HST/NICMOS Type 1 point sources and near-IR reverberation
• The WISSH Quasars Project I. Powerful ionised outflows in hyper-luminous quasars
• Correlated Multi-Waveband Variability in the Blazar 3C~279 from 1996 to 2007
• The 2-79 keV X-ray Spectrum of the Circinus Galaxy with NuSTAR, XMM-Newton and Chandra: a Fully Compton-Thick AGN
• High-Velocity Bipolar Molecular Emission from an AGN Torus
• On the origin of the Fe K-alpha line cores in Active Galactic Nuclei
• The broad band spectral variability of MCG-6-30-15 observed by NuSTAR and XMM-Newton
• The variable hard X-ray emission of NGC4945 as observed by NuSTAR
• Discovery of Kiloparsec Extended Hard X-ray Continuum and Fe K alpha from the Compton Thick AGN ESO428-G014
• Reverberation Mapping of the Broad-line Region in NGC 5548: Evidence for Radiation Pressure?
• The 1.4 GHz radio properties of hard X-ray selected AGN
• X-ray Variability of the Seyfert 1 Markarian 335: Power Spectrum and Time Lags
• Statistics of relativistically broadened Fe K-alpha lines in AGN
• Evidence for variability timescale dependent UV/X-ray delay in Seyfert 1 AGN NGC 7469
• Near Infrared Variability of obscured and unobscured X-ray selected AGN in the COSMOS field
• The Multi-Layer Variable Absorbers in NGC 1365 Revealed by XMM-Newton and NuSTAR
• Spatially resolved Fe K spectroscopy of NGC 4945
• The iron K feature in Narrow Line Seyfert 1's: evidence for a P Cygni profile?
• Extreme ultra-soft X-ray variability in an eROSITA observation of the Narrow-Line Seyfert 1 Galaxy 1H 0707-495
• A New Black Hole Mass Estimate for Obscured Active Galactic Nuclei
• The Eddington ratio-dependent changing look events in NGC 2992
• Timing evidence in determining the accretion state of the Seyfert galaxy NGC 3783
• Monitoring the Violent Activity from the Inner Accretion Disk of the Seyfert 1.9 Galaxy NGC 2992 with RXTE
• Elliptical Galaxy in the Making: The Dual Active Galactic Nuclei and Metal-enriched Halo of Mrk 273
• Simultaneous Millimeter-wave and X-ray monitoring of the Seyfert Galaxy NGC 7469
• A multiwavelength-motivated X-ray model for the Circinus Galaxy
• The kpc Scale Fe K$\alpha$ Emission in the Compton Thin Seyfert 2 Galaxy NGC 4388 resolved by Chandra
• The X-ray spectral and variability properties of typical radio-loud quasars
• Relativistic reflection in the average X-ray spectrum of AGN in the Véron-Cetty & Véron catalogue
• The intrinsic line width of the Fe Ka line of AGN

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