ASCA observations of Seyfert 1 galaxies: II. Relativistic Iron K-alpha emission

Abstract

We present evidence for widespread relativistic effects in the central regions of active galactic nuclei. In a sample of 18 Seyfert 1 galaxies observed by \asca, 14 show an iron K$\alpha$ line which is is resolved, with mean width ${\sigma }_{\mathrm{K}\alpha }=0.43\pm 0.12$~keV for a gaussian profile (Full Width at Half Maximum, FWHM$\sim 50,000$~km s${}^{-1}$). However, many of the line profiles are asymmetric. A strong red wing is indicative of gravitational redshifts close to a central black hole and accretion disk models provide an excellent description of the data. The peak energy of the line is 6.4~keV, indicating that it arises by fluorescence in near-neutral material. Our fits imply a low inclination for the disk in these Seyfert 1 galaxies, with a mean of 30°, consistent with orientation-dependent unification schemes. Differences in the line profiles from source-to-source imply slight variations in geometry, which cannot be accounted for solely by inclination. In most cases, we require that the line emission arises from a range of radii. Although a small contribution to the emission from a region other than the disk is not ruled out, it is not generally required and has little effect on our conclusions regarding the disk line. Our data are fit equally well with rotating (Kerr) and non-rotating (Schwarzschild) black hole models. We find a mean spectral index in the 3-10 keV range of $<{\Gamma }_{3-10}>=1.91\pm 0.07$ after accounting for the effects of reflection. Such observations probe the innermost regions of AGN, and arguably provide the best evidence yet obtained for the existence of super-massive black holes in the centers of active galaxies.

49 pages, 10 figures. LaTeX with encapsulated postscript. To appear in the Astrophysical Journal. Also available via http://lheawww.gsfc.nasa.gov/~nandra/pubs/paper2/abstract.html

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• The X-Ray Spectral Variability of Mrk 766

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• Close and distant reprocessing media in Mkn509 studied with BeppoSAX
• A prominent relativistic iron line in the Seyfert 1 MCG-02-14-009
• The Contribution of Particle Impact to the Production of Fe K Emission from Accreting Black Holes
• The iron $K_{\alpha }$ lines as a tool for magnetic field estimations in non-flat accretion flows
• Composite profile of the Fe K$\alpha$ spectral line emitted from a binary system of supermassive black holes
• Fourier-Resolved Spectroscopy of AGN using XMM-Newton data: I. The 3-10 keV band results
• Relativistic ionized accretion disc models of MCG--6-30-15
• Origin of the "Disk-Line" Feature in the X-Ray Energy Spectrum of a Seyfert Galaxy, NGC4151
• Investigating the origin of the Fe emission lines of the Seyfert 1 galaxy Mrk~205
• Non-Thermal Emission from AGN Coronae
• Active Galactic Nuclei at the Crossroads of Astrophysics
• Does the Iron K${}_{\alpha }$ Line of Active Galactic Nuclei Arise from the Cerenkov Line-like Radiation?
• Absorption at the dust sublimation radius and the dichotomy between X-ray and optical classification in the Seyfert galaxy H0557-385
• Discovery of a Nuclear X-Ray Source in NGC 7331: Evidence for a Massive Black Hole
• X-ray Spectroscopy and Variability of AGN Detected in the 2 Ms Chandra Deep Field-North Survey
• XMM-Newton spectroscopy of high redshift quasars
• XMM-Newton spectra of hard spectrum Rosat AGN: X-ray absorption and optical reddening
• Possible Evidence for a Truncated Thin Disk in Seyfert 1 Galaxy NGC4593
• Do all QSOs have the same black hole mass?
• Rms variability properties of the iron K alpha line in Seyfert galaxies
• Strong field effects on emission line profiles: Kerr black holes and warped accretion disks
• Broad-line Region Clouds orbiting an AGN sample
• On the peculiar properties of the narrow-line quasar PG 1543+489
• Non-thermal X-ray Emission: An Alternative to Cluster Cooling Flows?
• Probing the precession of the inner accretion disk in Cygnus X-1
• Amplification and variability of the AGN X-ray emission due to microlensing
• The obscured QSO 1SAX J1218.9+2958
• Far-Ultraviolet Spectroscopy Of Active Galactic Nuclei With AstroSat/UVIT
• X-ray Images of Hot Accretion Flows
• XMM-Newton Observation of Fe Kalpha emission from a BAL QSO: Mrk 231
• Radio/X-Ray Luminosity Relation for X-Ray Bright Galactic Nuclei: Implications on Weighing Supermassive Black Hole
• Influence of gravitational microlensing on broad absorption lines of QSOs: The case of the Fe K$\alpha$ line
• The flare model for X-ray variability of NGC 4258
• Atomic X-ray Spectroscopy of Accreting Black Holes
• Relativistic iron K alpha line detection in the Suzaku spectra of IC 4329A
• Ray-tracing in four and higher dimensional black holes: An analytical approximation
• Modeling time delays in the X-ray spectrum of the Seyfert galaxy MCG-6-30-15
• Spectral and polarimetric signatures of X-ray eclipses in AGN
• Astrophysics with the Laser Interferometer Space Antenna
• Impact of ionization and electron density gradients in X-ray reflection spectroscopy measurements
• Inferring Compton-thick AGN candidates at z>2 with Chandra using the >8 keV restframe spectral curvature
• A two zone model for the broad Iron line emission in MCG-6-30-15
• Probing the origin of the iron K_alpha line around stellar and supermassive black holes using X-ray polarimetry
• The NuSTAR view of the Seyfert Galaxy HE 0436-4717
• Coronal Line Forest AGN -- II. Analysis of the spectral energy distribution
• RE J2248-511 - Not all variable, ultrasoft, X-ray AGN have narrow Balmer lines
• A Deep XMM-Newton Observation of the Quasar 3C 287
• A Systematic Study of the Short-Term X-ray Variability of Seyfert Galaxies I. Diversity of the X-ray Rms Spectra
• Compact X-ray Sources in Nearby Galaxy Nuclei
• The shape of Fe K$\alpha$ line emitted from relativistic accretion disc around AGN black holes
• Pair Creation at Shocks: Application to the High Energy Emission of Compact objects
• BeppoSAX observations of the Seyfert 1 Galaxy NGC 3516
• Seyfert Galaxies and BeppoSAX
• Averaging the spectral shapes
• Gamma-ray burst: probe of a black hole
• Suzaku Confirms NGC~3660 is an Unabsorbed Seyfert 2
• The Relation between the Inclinations of Broad Line Regions and the Accretion Disk
• Searching for Black Holes in Space - the key role of X-ray observations
• Strong gravity and X-ray spectroscopy
• Interaction between disk and extended corona in a general relativistic framework
• On the Relation between the Inclination Angle of the Accretion Disk and the Broad-line Region in Active Galactic Nuclei
• The BeppoSAX X-ray view of reflection-dominated Seyfert Galaxies
• X-ray energy and power spectra of Seyfert 1 and Narrow Line Seyfert 1 galaxies: comparison to Black Hole Binaries
• The study of the circumnuclear environment of accreting supermassive black holes with realistic X-ray spectral models
• Probing the extremes of Seyfert activity: BeppoSAX observations of Narrow-Line Seyfert 1 galaxies
• Active galactic nuclei and gravitational redshifts