Rimmed and Rippled Accretion Disc Models to Explain AGN Continuum Lags

Abstract

We propose a solution to the problem of accretion disc sizes in active galactic nuclei being larger when measured by reverberation mapping than predicted by theory. Considering blackbody reprocessing on a disc with thickness profile $H(r)$, our solution invokes a steep rim or rippled structures irradiated by the central lamp-post. We model the continuum lags and the faint and bright disc spectral energy distribution (SED) in the best-studied case NGC 5548 (black hole mass $M=7\times 10^7{M}_{\odot }$, disc inclination $i=45^{\circ }$). With the lamp-post off, the observed disc SED requires a low accretion rate ($\dot{M}\sim 0.0014M_{\odot }$/yr) and high prograde black hole spin ($a\sim 0.93$). Reprocessing on the thin disc gives time lags increasing with wavelength but 3 times smaller than observed. Introducing a steep $H(r)$ rim, or multiple crests, near $r=5$ light days, reprocessing on their steep centre-facing slopes increases temperatures from $\sim 1500$ K to $\sim 6000$ K and this increases optical lags to match the lag data. Most of the disc surface maintains the cooler $T\propto r^{-3/4}$ temperature profile that matches the SED. The bright lamp-post may be powered by magnetic links tapping the black hole spin. The steep rim occurs near the sublimation radius for dust in the disc, as in the "failed disc wind model" for broad-line clouds. Lens-Thirring torques aligning the disc and black hole spin may also raise a warp and associated waves. In both scenarios, the small density scale height implied by the inferred value of $H(r)$ suggests possible marginal gravitational instability in the disc.

arXiv comment17 pages, 7 figures, accepted for publication in Monthly Notices of the Royal Astronomical Society

References in corpus (58)

• The Man Behind the Curtain: X-rays Drive the UV through NIR Variability in the 2013 AGN Outburst in NGC 2617
• Spectral Energy Distributions of T Tauri Stars With Passive Circumstellar Disks
• Hot Accretion Flows Around Black Holes
• Modeling the Time Variability of SDSS Stripe 82 Quasars as a Damped Random Walk
• A Global Three Dimensional Radiation Magneto-hydrodynamic Simulation of Super-Eddington Accretion Disks
• Selfgravity and QSO disks
• A review of quasi-periodic oscillations from black hole X-ray binaries: observation and theory
• The Quasar Accretion Disk Size -- Black Hole Mass Relation
• The Quasar Accretion Disk Size - Black Hole Mass Relation
• An Alternative Approach To Measuring Reverberation Lags in Active Galactic Nuclei
• Space Telescope and Optical Reverberation Mapping Project. III. Optical Continuum Emission and Broad-Band Time Delays in NGC 5548
• Space Telescope and Optical Reverberation Mapping Project. II. Swift and HST Reverberation Mapping of the Accretion Disk of NGC 5548
• Modeling reverberation mapping data II: dynamical modeling of the Lick AGN Monitoring Project 2008 dataset
• Testing thermal reprocessing in AGN accretion discs
• Magnetic Stress at the Marginally Stable Orbit: Altered Disk Structure, Radiation, and Black Hole Spin Evolution
• The origin of the Broad Line Region in Active Galactic Nuclei
• Total and Jet Blandford-Znajek Power in Presence of Accretion Disk
• Analytical protostellar disk models 1: the effect of internal dissipation and surface irradiation on the structure of disks and the location of the snow line around Sun-like stars
• A global look at X-ray time lags in Seyfert Galaxies
• CAIXA: a catalogue of AGN in the XMM-Newton archive III. Excess Variance Analysis
• Supermassive Stars in Quasar Disks
• Reverberation mapping of Active Galactic Nuclei: from X-ray corona to dusty torus
• The non-linear fluid dynamics of a warped accretion disc
• The First Swift Intensive AGN Accretion Disk Reverberation Mapping Survey
• X-ray Microlensing in RXJ1131-1231 and HE1104-1805
• Space Telescope and Optical Reverberation Mapping Project. I. Ultraviolet Observations of the Seyfert 1 Galaxy NGC 5548 with the Cosmic Origins Spectrograph on Hubble Space Telescope
• Accretion disk reverberation with Hubble Space Telescope observations of NGC 4593: evidence for diffuse continuum lags
• Global Radiation Magneto-hydrodynamic Simulations of Sub-Eddington Accretion Disks around Supermassive Black Holes
• Dust inflated accretion disc as the origin of the Broad Line Region in Active Galactic Nuclei
• The Variable Diffuse Continuum Emission of Broad Line Clouds
• On the size and location of the X-ray emitting coronae around black holes
• Tearing up the disc: how black holes accrete
• The Kozai-Lidov Mechanism in Hydrodynamical Disks
• The Spatial Structure of An Accretion Disk
• The Structure of the X-ray and Optical Emitting Regions of the Lensed Quasar Q 2237+0305
• The origin of the UV/optical lags in NGC 5548
• The evolution of a warped disc around a Kerr black hole
• Intensive disc-reverberation mapping of Fairall 9: 1st year of Swift & LCO monitoring
• Space Telescope and Optical Reverberation Mapping Project VI: reverberating Disk Models for NGC 5548
• Quantifying the Diffuse Continuum Contribution of BLR Clouds to AGN Continuum Inter-band Delays
• Modeling the UV/optical continuum time-lags in AGN
• Space Telescope and Optical Reverberation Mapping Project. IX. Velocity-Delay Maps for Broad Emission Lines in NGC 5548
• Accretion Disc Time Lag Distributions: Applying CREAM to Simulated AGN Light Curves
• Dynamics of warped accretion discs
• The Sloan Digital Sky Survey Reverberation Mapping Project: Accretion-Disk Sizes from Continuum Lags
• Evolution of warped and twisted accretion discs in close binary systems
• Profile variability of the H-alpha and H-beta broad emission lines in NGC5548
• Continuum reverberation mapping and a new lag-luminosity relationship for AGN
• Non-Blackbody Disks Can Help Explain Inferred AGN Accretion Disk Sizes
• Ringed accretion disks: equilibrium configurations
• Correlated X-ray/Ultraviolet/Optical Variability in NGC 6814
• The picture of BLR in 2.5-D FRADO: Dynamics & Geometry
• Global simulations of self-gravitating magnetized protoplanetary disks
• Evidence of a discontinuous disk structure around the Herbig Ae star HD 139 614
• The spectral energy distribution of the redshift 7.1 quasar ULAS J1120+0641
• Free Unstable Modes and Massive Bodies in Saturn's Outer B Ring
• On the global warping of a thin self-gravitating near Keplerian gaseous disk with application to the disk in NGC 4258
• Modeling Quasar UV/Optical Variability with the Corona-heated Accretion-disk Reprocessing (CHAR) Model

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