The reverberation signatures of rotating disc winds in active galactic nuclei

Abstract

The broad emission lines (BELs) in active galactic nuclei (AGN) respond to ionizing continuum variations. The time and velocity dependence of their response depends on the structure of the broad-line region: its geometry, kinematics and ionization state. Here, we predict the reverberation signatures of BELs formed in rotating accretion disc winds. We use a Monte Carlo radiative transfer and ionization code to predict velocity-delay maps for representative high- (C$IV$) and low-ionization (H$\alpha$) emission lines in both high- and moderate-luminosity AGN. Self-shielding, multiple scattering and the ionization structure of the outflows are all self-consistently taken into account, while small-scale structure in the outflow is modelled in the micro-clumping approximation. Our main findings are: (1) The velocity-delay maps of smooth/micro-clumped outflows often contain significant negative responses. (2)~The reverberation signatures of disc wind models tend to be rotation dominated and can even resemble the classic "red-leads-blue" inflow signature. (3) Traditional "blue-leads-red" outflow signatures can usually only be observed in the long-delay limit. (4) Our models predict lag-luminosity relationships similar to those inferred from observations, but systematically underpredict the observed centroid delays. (5) The ratio between "virial product" and black hole mass predicted by our models depends on viewing angle. Our results imply that considerable care needs to be taken in interpreting data obtained by observational reverberation mapping campaigns. In particular, basic signatures such as "red-leads-blue", "blue-leads-red" and "blue and red vary jointly" are not always reliable indicators of inflow, outflow or rotation. This may help to explain the perplexing diversity of such signatures seen in observational campaigns to date.

15 pages, 17 figures, 2 tables. Accepted by MNRAS 20/7/2017

References in corpus (11)

• The diversity of quasars unified by accretion and orientation
• Space Telescope and Optical Reverberation Mapping Project. II. Swift and HST Reverberation Mapping of the Accretion Disk of NGC 5548
• The Intrinsic Fraction of Broad Absorption Line Quasars
• 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
• The Black Hole Mass Scale of Classical and Pseudo Bulges in Active Galaxies
• Modeling reverberation mapping data I: improved geometric and dynamical models and comparison with cross-correlation results
• Double-peaked profiles: ubiquitous signatures of disks in the Broad Emission Lines of Active Galactic Nuclei
• First Results from the Lick AGN Monitoring Project: The Mass of the Black Hole in Arp 151
• Interpreting broad emission-line variations I : Factors influencing the emission-line response
• Broad-line region structure and kinematics in the radio galaxy 3C 120
• The Geometry and Ionization Structure of the Wind in the Eclipsing Nova-like Variables RW Tri and UX UMa

Cited by in corpus (10)

• The spatially resolved broad line region of IRAS 09149-6206
• Stratified disc wind models for the AGN broad-line region: ultraviolet, optical and X-ray properties
• Reverberation Mapping Measurements of Black Hole Masses and Broad-Line Region Kinematics in Mrk 817 and NGC 7469
• Radiation hydrodynamics models of Active Galactic Nuclei: Beyond the central parsec
• Supermassive Black Hole and Broad-line Region in NGC~5548: Results from Five-season Reverberation Mapping
• ALMA resolves the remarkable molecular jet and rotating wind in the extremely radio-quiet galaxy NGC 1377
• Do Reverberation Mapping Analyses Provide an Accurate Picture of the Broad Line Region?
• A disc wind model for blueshifts in quasar broad emission lines
• SIROCCO: A Publicly Available Monte Carlo Ionization and Radiative Transfer Code for Astrophysical Outflows
• Spectral-timing of AGN ionized outflows with Athena