Likelihood for Detection of Sub-parsec Supermassive Black Hole Binaries in Spectroscopic Surveys

Abstract

Motivated by observational searches for sub-parsec supermassive black hole binaries (SBHBs) we develop a modular analytic model to determine the likelihood for detection of SBHBs by ongoing spectroscopic surveys. The model combines the parametrized rate of orbital evolution of SBHBs in circumbinary disks with the selection effects of spectroscopic surveys and returns a multivariate likelihood for SBHB detection. Based on this model we find that in order to evolve into the detection window of the spectroscopic searches from larger separations in less than a Hubble time, $10^8{M}_{\odot }$ SBHBs must, on average, experience angular momentum transport faster than that provided by a disk with accretion rate $0.06{\dot{M}}_E$. Spectroscopic searches with yearly cadence of observations are in principle sensitive to binaries with orbital separations $<\mathrm{few}\times 10^4{r}_g$ ($r_g=GM/c^2$ and $M$ is the binary mass), and for every one SBHB in this range there should be over 200 more gravitationally bound systems with similar properties, at larger separations. Furthermore, if spectra of all SBHBs in this separation range exhibit the AGN-like emission lines utilized by spectroscopic searches, the projection factors imply five undetected binaries for each observed $10^8{M}_{\odot }$ SBHB with mass ratio $0.3$ and orbital separation $10^4{r}_g$ (and more if some fraction of SBHBs is inactive). This model can be used to infer the most likely orbital parameters for observed SBHB candidates and to provide constraints on the rate of orbital evolution of SBHBs, if observed candidates are shown to be genuine binaries.

Accepted to ApJ (16 pages, 11 figures). Revised version includes referee's comments

References in corpus (17)

• A Compact Supermassive Binary Black Hole System
• A massive binary black-hole system in OJ287 and a test of general relativity
• The Population of Viscosity- and Gravitational Wave-Driven Supermassive Black Hole Binaries Among Luminous AGN
• The Lick AGN Monitoring Project 2011: Spectroscopic Campaign and Emission-Line Light Curves
• Chandra Discovery of a Binary Active Galactic Nucleus in Mrk 739
• Growing Massive Black Hole Pairs in Minor Mergers of Disk Galaxies
• The First Spectroscopically Resolved Sub-parsec Orbit of a Supermassive Binary Black Hole
• Constraining the Orbit of Supermassive Black Hole Binary 0402+379
• Modeling of Emission Signatures of Massive Black Hole Binaries: I Methods
• Orbital Decay of Supermassive Black Hole Binaries in Clumpy Multiphase Merger Remnants
• A Systematic Search for Periodically Varying Quasars in Pan-STARRS1: An Extended Baseline Test in Medium Deep Survey Field MD09
• NuSTAR Resolves the First Dual AGN above 10 keV in SWIFT J2028.5+2543
• Searching for Binary Supermassive Black Holes via Variable Broad Emission Line Shifts: Low Binary Fraction
• Repeated Imaging of Massive Black Hole Binary Orbits with Millimeter Interferometry: measuring black hole masses and the Hubble constant
• Supermassive Black Hole Binaries: The Search Continues
• Linking the fate of massive black hole binaries to the active galactic nuclei luminosity function
• Broad HI absorption in the candidate binary black-hole 4C37.11 (B2 0402+379)

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• Constraining Sub-Parsec Binary Supermassive Black Holes in Quasars with Multi-Epoch Spectroscopy. III. Candidates from Continued Radial Velocity Tests
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• Emission Signatures from Sub-parsec Binary Supermassive Black Holes III: Comparison of Models with Observations
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