Emission Signatures from Sub-parsec Binary Supermassive Black Holes I: Diagnostic Power of Broad Emission Lines

Abstract

Motivated by advances in observational searches for sub-parsec supermassive black hole binaries (SBHBs) made in the past few years we develop a semi-analytic model to describe spectral emission line signatures of these systems. The goal of this study is to aid the interpretation of spectroscopic searches for binaries and help test one of the leading models of binary accretion flows in the literature: SBHB in a circumbinary disk. In this work we present the methodology and a comparison of the preliminary model with the data. We model SBHB accretion flows as a set of three accretion disks: two mini-disks that are gravitationally bound to the individual black holes and a circumbinary disk. Given a physically motivated parameter space occupied by sub-parsec SBHBs, we calculate a synthetic database of nearly 15 million broad optical emission line profiles and explore the dependence of the profile shapes on characteristic properties of SBHBs. We find that the modeled profiles show distinct statistical properties as a function of the semi-major axis, mass ratio, eccentricity of the binary, and the degree of alignment of the triple disk system. This suggests that the broad emission line profiles from SBHB systems can in principle be used to infer the distribution of these parameters and as such merit further investigation. Calculated profiles are more morphologically heterogeneous than the broad emission lines in observed SBHB candidates and we discuss improved treatment of radiative transfer effects which will allow direct statistical comparison of the two groups.

27 pages, 20 figures, accepted to ApJ

References in corpus (20)

• X-ray reverberation around accreting black holes
• Massive black hole binary mergers within sub-pc scale gas discs
• Global General Relativistic MHD Simulation of a Tilted Black-Hole Accretion Disk
• Rapid Formation of Supermassive Black Hole Binaries in Galaxy Mergers with Gas
• The Population of Viscosity- and Gravitational Wave-Driven Supermassive Black Hole Binaries Among Luminous AGN
• Alignment of the spins of supermassive black holes prior to coalescence
• Supermassive black hole binaries in gaseous and stellar circumnuclear discs: orbital dynamics and gas accretion
• Alignment of Magnetized Accretion Disks and Relativistic Jets with Spinning Black Holes
• A Candidate Sub-Parsec Supermassive Binary Black Hole System
• Binary Black-Hole Mergers in Magnetized Disks: Simulations in Full General Relativity
• Growing Massive Black Hole Pairs in Minor Mergers of Disk Galaxies
• Spectroscopic Indication for a Centi-parsec Supermassive Black Hole Binary in the Galactic Center of NGC 5548
• Three Dimensional MHD Simulation of Circumbinary Accretion Disks -2. Net Accretion Rate
• The First Spectroscopically Resolved Sub-parsec Orbit of a Supermassive Binary Black Hole
• General Relativistic Simulations of Magnetized Plasmas around Merging Supermassive Black Holes
• Modeling of Emission Signatures of Massive Black Hole Binaries: I Methods
• Orbital Decay of Supermassive Black Hole Binaries in Clumpy Multiphase Merger Remnants
• Supermassive Black Hole Binaries: The Search Continues
• Interpreting the Variability of Double-Peaked Emission Lines in Active Galactic Nuclei with Stochastically Perturbed Accretion Disk Models
• The nature of massive black hole binary candidates: II. Spectral energy distribution atlas

Cited by in corpus (26)

• Black holes, gravitational waves and fundamental physics: a roadmap
• The Quest for Dual and Binary Supermassive Black Holes: A Multi-Messenger View
• Evidence for periodicity in 43 year-long monitoring of NGC 5548
• Constraining Sub-Parsec Binary Supermassive Black Holes in Quasars with Multi-Epoch Spectroscopy. III. Candidates from Continued Radial Velocity Tests
• Monitoring AGNs with Hβ Asymmetry. I. First Results: Velocity-resolved Reverberation Mapping
• Searching for Binary Supermassive Black Holes via Variable Broad Emission Line Shifts: Low Binary Fraction
• Disks Around Merging Binary Black Holes: From GW150914 to Supermassive Black Holes
• X-ray Structure between the Innermost Disk and Optical Broad Line Region in NGC 4151
• Emission Signatures from Sub-parsec Binary Supermassive Black Holes II: Effect of Accretion Disk Wind on Broad Emission Lines
• An Improved Test of the Binary Black Hole Hypothesis for Quasars with Double-peaked Broad Balmer Lines
• Considerations for the Observability of Kinematically Offset Binary AGN
• Emission Signatures from Sub-parsec Binary Supermassive Black Holes III: Comparison of Models with Observations
• Likelihood for Detection of Sub-parsec Supermassive Black Hole Binaries in Spectroscopic Surveys
• No Evidence for Periodic Variability in the Light Curve of Active Galaxy J0045+41
• Detection of periodic signals in AGN red noise light curves: empirical tests on the Auto-Correlation Function and Phase Dispersion Minimization
• Detecting subparsec super-massive binary black holes: Long termmonitoring perspective
• Broad-line region configuration of the supermassive binary black hole candidate PG1302-102 in the relativistic Doppler boosting scenario
• Predicting the broad lines polarization emitted by supermassive binary black holes
• Pulsar Timing Array Constraints on the Merger Timescale of Subparsec Supermassive Black Hole Binary Candidates
• Differential Interferometric Signatures of Close Binaries of Supermassive Black Holes in Active Galactic Nuclei: II. Merged Broad Line Regions
• Astrophysics with the Laser Interferometer Space Antenna
• Testing compact massive black hole binary candidates through multi-epoch spectroscopy
• Detection of eccentric close-binary supermassive black holes with incomplete interferometric data
• The Host Galaxies of PTA Sources: Converting Supermassive BH Binary Parameters into EM Observables
• The broad emission line asymmetry in low mass ratio of supermassive binary black holes on elliptical orbits
• Detection of quasars in the time domain