Differential Interferometric Signatures of Close Binaries of Supermassive Black Holes in Active Galactic Nuclei: II. Merged Broad Line Regions

Abstract

Pairs of supermassive black holes (SMBHs) at different stages are natural results of galaxy mergers in the hierarchical framework of galaxy formation and evolution. However, identifications of close binaries of SMBHs (CB-SMBHs) with sub-parsec separations in observations are still elusive. Recently, unprecedented spatial resolutions achieved by GRAVITY/GRAVITY+ onboard The Very Large Telescope Interferometer through spectroastrometry (SA) provide new opportunities to resolve CB-SMBHs. Differential phase curves of CB-SMBHs with two independent broad-line regions (BLRs) are found to have distinguished characteristic structures from a single BLR \citep{songsheng2019}. Once the CB-SMBH evolves to the stage where BLRs merge to form a circumbinary BLR, it will hopefully be resolved by the pulsar timing array (PTA) in the near future as sources of nano-hertz gravitational waves. In this work, we use a parameterized model for circumbinary BLRs to calculate line profiles and differential phase curves for SA observations. We show that both profiles and phase curves exhibit asymmetries caused by the Doppler boosting effect of accretion disks around individual black holes, depending on the orbital parameters of the binary and geometries of the BLR. We also generate mock SA data using the model and then recover orbital parameters by fitting the mock data. Degeneracies between parameters contribute greatly to uncertainties of parameters but can be eased through joint analysis of multiple-epoch SA observations and reverberation mappings.

arXiv comment21 pages, 17 figures, accepted by ApJ

References in corpus (68)

• Coevolution (Or Not) of Supermassive Black Holes and Host Galaxies
• dynesty: A Dynamic Nested Sampling Package for Estimating Bayesian Posteriors and Evidences
• Reverberation Measurements for 17 Quasars and the Size-Mass-Luminosity Relations in Active Galactic Nuclei
• The Galactic Center Massive Black Hole and Nuclear Star Cluster
• Long-Term Stability of Planets in Binary Systems
• The Low-Luminosity End of the Radius-Luminosity Relationship for Active Galactic Nuclei
• Are the Variations in Quasar Optical Flux Driven by Thermal Fluctuations?
• Gravitational-wave sensitivity curves
• Central Masses and Broad-Line Region Sizes of Active Galactic Nuclei: I. Comparing the Photoionization and Reverberation Techniques
• First Light for GRAVITY: Phase Referencing Optical Interferometry for the Very Large Telescope Interferometer
• The Evolution of Galaxy Structure over Cosmic Time
• Systematic Effects in Measurement of Black Hole Masses by Emission-Line Reverberation of Active Galactic Nuclei: Eddington Ratio and Inclination
• A Compact Supermassive Binary Black Hole System
• Massive black hole binary mergers within sub-pc scale gas discs
• Kinematics of Parsec-Scale Jets of Gamma-Ray Blazars at 43~GHz within the VLBA-BU-BLAZAR Program
• Upper bounds on the low-frequency stochastic gravitational wave background from pulsar timing observations: current limits and future prospects
• The International Pulsar Timing Array second data release: Search for an isotropic Gravitational Wave Background
• The Role of Gas in the Merging of Massive Black Holes in Galactic Nuclei. II. Black Hole Merging in a Clumpy Disk
• A systematic search for close supermassive black hole binaries in the Catalina Real-Time Transient Survey
• Dynamic nested sampling: an improved algorithm for parameter estimation and evidence calculation
• Tracing Black Hole Mergers Through Radio Lobe Morphology
• Long Term Evolution of Massive Black Hole Binaries
• False periodicities in quasar time-domain surveys
• Gravitational waves from resolvable massive black hole binary systems and observations with Pulsar Timing Arrays
• The Deep2 Galaxy Redshift Survey: Evolution of Close Galaxy Pairs and Major-Merger Rates Up to z ~ 1.2
• A Population of Short-Period Variable Quasars from PTF as Supermassive Black Hole Binary Candidates
• Spatially resolved rotation of the broad-line region of a quasar at sub-parsec scale
• Dynamically Close Galaxy Pairs and Merger Rate Evolution in the CNOC2 Redshift Survey
• Reverberation Measurements of the Inner Radius of the Dust Torus in 17 Seyfert Galaxies
• The Structure of the Broad Line Region in AGN: I. Reconstructed Velocity-Delay Maps
• Relativistic boost as the cause of periodicity in a massive black-hole binary candidate
• A Stochastic Model for the Luminosity Fluctuations of Accreting Black Holes
• Identifying Supermassive Black Hole Binaries with Broad Emission Line Diagnosis
• A 1.75 kpc/h Separation Dual AGN at z=0.36 in the COSMOS Field
• Modeling reverberation mapping data I: improved geometric and dynamical models and comparison with cross-correlation results
• The Lick AGN Monitoring Project: Velocity-Delay Maps from the Maximum-Entropy Method for Arp 151
• The broad emission-line region: the confluence of the outer accretion disc with the inner edge of the dusty torus
• FIRST `Winged' and `X'-shaped Radio Source Candidates
• Supermassive Black Holes with High Accretion Rates in Active Galactic Nuclei. VI. Velocity-resolved Reverberation Mapping of H$\beta$ Line
• Spectroscopic Indication for a Centi-parsec Supermassive Black Hole Binary in the Galactic Center of NGC 5548
• Super-massive binary black holes and emission lines in active galactic nuclei
• The First Spectroscopically Resolved Sub-parsec Orbit of a Supermassive Binary Black Hole
• Equatorial scattering and the structure of the broad-line region in Seyfert nuclei: evidence for a rotating disc
• Supermassive Black Hole Binary Candidates from the Pan-STARRS1 Medium Deep Survey
• Exploring the inner region of Type 1 AGNs with the Keck interferometer
• The central parsec of NGC 3783: a rotating broad emission line region, asymmetric hot dust structure, and compact coronal line region
• Stochastic modeling of multiwavelength variability of the classical BL Lac object OJ 287 on timescales ranging from decades to hours
• The resolved size and structure of hot dust in the immediate vicinity of AGN
• Radio-loud Narrow Line Seyfert 1 under a different perspective: a revised black hole mass estimate from optical spectropolarimetry
• Reverberation Mapping of the Broad-line Region in NGC 5548: Evidence for Radiation Pressure?
• A parallax distance to 3C 273 through spectroastrometry and reverberation mapping
• Multi-messenger Time-domain Signatures Of Supermassive Black Hole Binaries
• A Possible ~20 yr Periodicity in Long-term Optical Photometric and Spectral Variations of the Nearby Radio-Quiet Active Galactic Nucleus Ark 120
• Emission Signatures from Sub-parsec Binary Supermassive Black Holes I: Diagnostic Power of Broad Emission Lines
• Emission Signatures from Sub-parsec Binary Supermassive Black Holes II: Effect of Accretion Disk Wind on Broad Emission Lines
• Kinematic signatures of reverberation mapping of close binaries of supermassive black holes in active galactic nuclei
• Supermassive black holes with high accretion rates in active galactic nuclei. VII. Reconstruction of velocity-delay maps by maximum entropy method
• Considerations for the Observability of Kinematically Offset Binary AGN
• Emission Signatures from Sub-parsec Binary Supermassive Black Holes III: Comparison of Models with Observations
• Kinematic signatures of reverberation mapping of close binaries of supermassive black holes in active galactic nuclei. II. Atlas of two-dimensional transfer functions
• Kinematic signatures of reverberation mapping of close binaries of supermassive black holes in active galactic nuclei III. The case of elliptical orbits
• Variation of Broad Emission Lines from QSOs with Optical/UV Periodicity to Test the Interpretation of Supermassive Binary Black Holes
• A New Approach for Measuring Power Spectra and Reconstructing Time Series in Active Galactic Nuclei
• Measuring black hole mass of type I active galactic nuclei by spectropolarimetry
• Differential Interferometric Signatures of Close Binaries of Supermassive Black Holes in Active Galactic Nuclei
• Spiral Arms in Broad-line Regions of Active Galactic Nuclei. I. Reverberation and Differential Interferometric Signals of Tightly Wound Cases
• Spectroastrometric Reverberation Mapping of Broad-line Regions
• Differential interferometry of close binary of supermassive black holes in an elliptical configuration

Cited by in corpus (3)

• Unveiling the solution to the final-parsec problem by combining milli-Hertz gravitational-wave observation and AGN survey
• Probing $H_0$ and resolving AGN disks with ultrafast photon counters
• On Variation of Light Curves and Broad Emission Lines for Periodic QSOs from co-rotating Supermassive binary black holes in elliptical orbits