Broad iron emission lines in Seyfert Galaxies - re-condensation of gas onto an inner disk below the ADAF

Abstract

Recent observations of Seyfert 1 AGN with Chandra, XMM-Newton and Suzaku revealed broad iron K_alpha emission lines, some relativistically blurred. For galactic black hole X-ray binaries XMM-Newton spectra during hard state also reveal the presence of a relativistic iron emission line and a thermal component, interpreted as an indication for a weak inner cool accretion disk underneath a hot corona. These thermal components were found after the transition from soft to hard spectral state and can be understood as sustained by re-condensation of gas from an advection-dominated flow (ADAF) onto the disk. In view of the similarity of accretion flows around stellar mass and supermassive black holes we discuss whether the broad iron emission lines in Seyfert 1 AGN can be understood as arising from a similar accretion flow geometry. We derive Eddington-scaled accretion rates for Seyfert galaxies with strong lines in samples of Miller (2007) and Nandra et al. (2007). For the evaluation we use the observed X-ray luminosity, bolometric corrections and black hole masses from literature, most values taken from Fabian and Vasudevan (2009). Rates derived are less than 0.1 of the Eddington rate for more than half of the sources. For 10^7 to 10^8 solar mass black holes in Seyfert 1 AGN this limit corresponds to 0.01 to 0.2 solar masses per year. Our investigation shows that for quite a number of Seyfert AGN in hard spectral state iron emission lines can arise from an inner weak disk surrounded by an ADAF as predicted by the re-condensation model. Some of the remaining sources with higher accretion rates may be in a spectral state comparable to the "very high" state of LMXBs. (abridged)

9 pages, 3 figures, accepted for publication in Astronomy and Astrophysics

References in corpus (23)

• X-ray Properties of Black-Hole Binaries
• Modelling the behaviour of accretion flows in X-ray binaries
• An XMM-Newton survey of broad iron lines in Seyfert galaxies
• Piecing Together the X-ray Background: Bolometric Corrections for Active Galactic Nuclei
• Advection-Dominated Accretion and the Black Hole Event Horizon
• Relativistic X-ray Lines from the Inner Accretion Disks Around Black Holes
• Simultaneous X-ray/optical/UV snapshots of active galactic nuclei from XMM-Newton: spectral energy distributions for the reverberation mapped sample
• Radiatively Inefficient Accretion in Nearby Galaxies
• A Long, Hard Look at the Low-Hard State in Accreting Black Holes
• The Hard X-ray Spectral Slope as an Accretion-Rate Indicator in Radio-Quiet Active Galactic Nuclei
• An absorption origin for the X-ray spectral variability of MCG-6-30-15
• A Prominent Accretion Disk in the Low-Hard State of the Black Hole Candidate SWIFT J1753.5-0127
• A Search for "Dwarf" Seyfert Nuclei. VII. A Catalog of Central Stellar Velocity Dispersions of Nearby Galaxies
• The Existence of Inner Cool Disks in the Low Hard State of Accreting Black Holes
• On the origin of the Fe K-alpha line cores in Active Galactic Nuclei
• Broadband X-ray Spectra of GX 339-4 and the Geometry of Accreting Black Holes in the Hard State
• Re-condensation from an ADAF into an inner disk - the intermediate state of black hole accretion?
• Spectral-timing evidence for a Very High State in the Narrow Line Seyfert 1 Ark 564
• On the Properties of Inner Cool Disks in the Hard State of Black Hole X-Ray Transient Systems
• The Energy-dependent X-ray Timing Characteristics of the Narrow Line Seyfert 1 Mkn 766
• Consistency of the black hole mass determination in AGN from the reverberation and the X-ray excess variance method
• The Spectral Features of Disk and Corona with Mass Evaporation in the Low/Hard State
• XMM-Newton observation of Mrk 110

Cited by in corpus (22)

• X-ray variability of 104 active galactic nuclei. XMM-Newton power-spectrum density profiles
• Swift monitoring of NGC 4151: Evidence for a Second X-ray/UV Reprocessing
• Central Regions of Barred Galaxies: Two-Dimensional Non-self-gravitating Hydrodynamic Simulations
• Formation of Magnetically Truncated Accretion Disks in 3D Radiation-Transport Two-Temperature GRMHD Simulations
• On the multi-wavelength variability of Mrk 110: Two components acting at different timescales
• Clumpy accretion onto black holes. I. Clumpy-ADAF structure and radiation
• The luminosity-dependent contribution from the broad line region to the wavelength-dependent lags in Mrk 110
• Nuclear Spiral Shocks and Induced Gas Inflows in Weak Oval Potentials
• A Cigale module tailored (not only) for Low-Luminosity AGN
• Coronae above accretion disks around black holes: The effect of Compton cooling
• The self-similar structure of advection-dominated discs with outflow and radial viscosity
• Reflection nebulae in the Galactic Center: the case for soft X-ray imaging polarimetry
• Accretion in active galactic nuclei and disk-jet coupling
• Interaction of the accretion flows in corona and disk near the black hole in AGN
• The long-term broad-line responsivity in MKN 110
• Exploring the Link between the X-ray Power Spectra and Energy Spectra of Active Galactic Nuclei
• The Profiles of Fe Kα Line From the Inhomogeneous Accretion Flow
• On the Zeeman Effect in Magnetically-Arrested Disks
• Self-similar structure of resistive ADAFs with outflow and large-scale magnetic field
• Long Term Reverberation Mapping of Iron Coronal Lines in MKN 110
• Flares in the Changing Look AGN Mrk 590. II: Deep X-ray observations reveal a Comptonizing inner accretion flow
• The UV/optical Continuum Reverberation Mapping of Eight Active Galactic Nuclei with Swift: Further Evidence for the Outer Component