Predicting the broad lines polarization emitted by supermassive binary black holes

Abstract

Some Type-1 active galactic nuclei (AGNs) are showing extremely asymmetric Balmer lines with the broad peak redshifted or blueshifted by thousands of km/s. These AGNs may be good candidates for supermassive binary black holes (SMBBHs). The complex line shapes can be very well due to the complex kinematics of the two broad line regions (BLRs). Therefore another methods should be applied to confirm the SMBBHs. One of them is spectropolarimetry. We rely on numerical modeling of the polarimetry of binary black holes systems since polarimetry is sensitive to geometry, in order to find specific influence of supermassive binary black hole (SMBBH) geometry and dynamics on polarized parameters across the broad line profiles. We apply our method to SMBBHs in which both components are assumed to be AGNs with distances at the sub-pc scale. We use a Monte Carlo radiative transfer code that simulates the geometry, dynamics and emission of a binary system where two black holes are getting increasingly closer. Each gravitational well is accompanied by its own BLR and the whole system is surrounded by an accretion flow from the distant torus. We examine the emission line deformation and predict the polarization that could be observed. We model broad line polarization for various BLR geometries with complex kinematics. We find that the presence of SMBBHs can produce complex polarization angle profiles and strongly affect the polarized and unpolarized line profiles. Depending on the phase of the SMBBH, the resulting double-peaked emission lines either show red or blue peak dominance, or both the peak can have the same intensity. In some cases, the whole line profile appears as a single Gaussian line, hiding the true nature of the source. Our results suggest that observations with the high resolution spectropolarimetry of optical broad emission lines could play an important role in detecting sub-pc SMBBHs.

20 pages, 24 pictures, accepted to A&A

References in corpus (52)

• Observation of Gravitational Waves from a Binary Black Hole Merger
• Coevolution (Or Not) of Supermassive Black Holes and Host Galaxies
• Central Masses and Broad-Line Region Sizes of Active Galactic Nuclei. II. A Homogeneous Analysis of a Large Reverberation-Mapping Database
• The Assembly and Merging History of Supermassive Black Holes in Hierarchical Models of Galaxy Formation
• The Relationship Between Luminosity and Broad-Line Region Size in Active Galactic Nuclei
• AGN Black Hole Masses and Bolometric Luminosities
• Gravitational waves from binary supermassive black holes missing in pulsar observations
• Massive black hole binary mergers within sub-pc scale gas discs
• An Eccentric Circumbinary Accretion Disk and the Detection of Binary Massive Black Holes
• A systematic search for close supermassive black hole binaries in the Catalina Real-Time Transient Survey
• Alignment of the spins of supermassive black holes prior to coalescence
• Direct Formation of Supermassive Black Holes via Multi-Scale Gas Inflows in Galaxy Mergers
• Completion of a Survey and Detailed Study of Double-Peaked Emission Lines in Radio-Loud AGNs
• A Large Systematic Search for Recoiling and Close Supermassive Binary Black Holes
• A Candidate Sub-Parsec Supermassive Binary Black Hole System
• Near Infrared Spectroscopy of High Redshift Active Galactic Nuclei. I. A Metallicity-Accretion Rate Relationship
• Circumbinary MHD Accretion into Inspiraling Binary Black Holes
• What broad emission lines tell us about how active galactic nuclei work
• Dual black holes in merger remnants. II: spin evolution and gravitational recoil
• Identifying Supermassive Black Hole Binaries with Broad Emission Line Diagnosis
• Modeling optical and UV polarization of AGNs I. Imprints of individual scattering regions
• A Spectropolarimetric Atlas of Seyfert 1 Galaxies
• The formation of galaxy stellar cores by the hierarchical merging of supermassive black holes
• 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
• 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
• Evidence For A Precessing Accretion Disk in the Nucleus of NGC 1097
• Polarized Broad-Line Emission from Low-Luminosity Active Galactic Nuclei
• Modeling optical and UV polarization of AGNs II. Polarization imaging and complex reprocessing
• Black Hole Masses of Active Galaxies with Double-Peaked Balmer Emission Lines
• Alignment of supermassive black hole binary orbits and spins
• The Millennium Galaxy Catalogue: The $M_{bh}$--$L_{spheroid}$ derived supermassive black hole mass function
• Modeling optical and UV polarization of AGNs III. From uniform-density to clumpy regions
• Spectropolarimetric evidence for a kicked supermassive black hole in the Quasar E1821+643
• A Measurement of the Black-Hole Mass in NGC 1097 using ALMA
• Variability of Active Galactic Nuclei from the Optical to X-ray Regions
• AGN Black hole mass estimates using polarization in broad emission Lines
• Spectral optical monitoring of the double peaked emission line AGN Arp 102B: II. Variability of the broad line properties
• Black Hole Mass Estimates and Rapid Growth of Supermassive Black Holes in Luminous $z\sim$ 3.5 Quasars
• Modeling optical and UV polarization of AGNs V. Dilution by interstellar polarization and the host galaxy
• Variability in Spectropolarimetric properties of Sy 1.5 galaxy Mrk 6
• Emission Signatures from Sub-parsec Binary Supermassive Black Holes I: Diagnostic Power of Broad Emission Lines
• The effect of the quasar H1821+643 on the surrounding intracluster medium: revealing the underlying cooling flow
• Polarization in lines - a new method for measuring black hole masses in active galaxies
• First long-term optical spectro-photometric monitoring of a binary black hole candidate E1821+643: I. Variability of spectral lines and continuum
• Off-axis irradiation and the polarization of broad emission lines in active galactic nuclei
• Spectropolarimetric monitoring of active galaxy 3C390.3 with 6m telescope SAO RAS in the period 2009-2014
• Line shifts and sub-pc super-massive binary black holes
• Enhanced MHD transport in astrophysical accretion flows: turbulence, winds and jets
• Constraining Recoiling Velocities of Black Holes Ejected by Gravitational Radiation in Galaxy Mergers

Cited by in corpus (8)

• Spectropolarimetry of the changing-look active galactic nucleus Mrk 1018
• 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
• Linear Spectropolarimetric Analysis of Fairall 9 with VLT/FORS2
• Polarimetry of the potential binary supermassive black hole system in J1430+2303
• Optical Spectropolarimetric Variability Properties in Blazars PKS 0637-75 and PKS 1510-089
• Polarization in broad emission lines of Active Galactic Nuclei
• Binary black hole signatures in polarized light curves