scholarly journals Dynamical evidence from the sub-parsec counter-rotating disc for a close binary of supermassive black holes in NGC 1068

2020 ◽  
Vol 497 (1) ◽  
pp. 1020-1028 ◽  
Author(s):  
Jian-Min Wang ◽  
Yu-Yang Songsheng ◽  
Yan-Rong Li ◽  
Pu Du ◽  
Zhe Yu
Keyword(s):  
Black Holes ◽  
Supermassive Black Holes ◽  
Dynamical Analysis ◽  
Close Binary ◽  
Rotating Disc ◽  
Speed Up ◽  
Ngc 1068 ◽  
Γ Rays ◽  
Tidal Torques ◽  
Cold Dust

ABSTRACT A puzzle in NGC 1068 is how to secularly maintain the counter-rotating disc (CRD) from 0.2 to $7\,$ pc unambiguously detected by recent ALMA observations of molecular gas. Upon further dynamical analysis, we find that the Kelvin–Helmholtz (KH) instability (KHI) results in an unavoidable catastrophe for the disc developed at the interface between the reversely rotating parts. We demonstrate that a close binary of supermassive black holes (CB-SMBHs) provides tidal torques to prevent the disc from the KH catastrophe and are led to the conclusion that there is a CB-SMBH at the centre of NGC 1068. The binary is composed of black holes with a separation of $0.1\,$ pc from GRAVITY/VLTI observations, a total mass of 1.3 × 107 M⊙ and a mass ratio of ∼0.3 estimated from the angular momentum (AM) budget of the global system. The KHI gives rise to a gap without cold gas at the velocity interface that overlaps with the observed gap of hot and cold dust regions. Releases of kinetic energies from the KHI of the disc are in agreement with observed emissions in radio and γ-rays. Such a binary is shrinking on a time-scale much longer than the local Hubble time via gravitational waves, however, the KHI leads to an efficient annihilation of the orbital AM and a speed-up merge of the binary, providing a new mechanism for solving the long-standing issue of ‘final parsec problem’. Future observations of GRAVITY+/VLTI are expected to be able to spatially resolve the CB-SMBHs suggested in this paper.

scholarly journals Investigating close binary supermassive black holes at high angular resolution

2021 ◽  
pp. 1-16
Author(s):  
A. Kovacevic
Keyword(s):  
Black Holes ◽  
Supermassive Black Holes ◽  
High Mass ◽  
Close Binary ◽  
Close Binaries ◽  
High Angular Resolution ◽  
Mutual Distance ◽  
Galaxy Mergers ◽  
Orbital Parameters ◽  
Reverberation Mapping

Gravitational waves (GW) in the nano-Hz domain are expected to be radiated by close-binaries of supermassive black holes (CB-SMBHs; components bound in a Keplerian binary at mutual distance less than ~ 0.1 pc), which are relicts of galaxy mergers and anticipated to be measured via the Pulsar Timing Array (PTA) technique. The challenge of present CB-SMBH investigations is that their signatures are elusive and not easily disentangled from a single SMBH. PTAs will typically have a glimpse of an early portion of the binary inspiral to catch the frequency evolution of the binary only with sufficiently high mass and initially high eccentricity. Thus, we have to make use of electromagnetic observations to determine orbital parameters of CB-SMBHs and test nano-Hz GW properties. The 2D reverberation mapping (RM) is a powerful tool for probing kinematics and geometry of ionized gas in the SMBHs (single or binary) vicinity, yet it can lose information due to projection on the line of sight of the observer. Nevertheless, spectroastrometry with AMBER, GRAVITY, and successors can provide an independent measurement of the emitting region's size, geometry, and kinematics. These two techniques combined can resolve CB-SMBHs. In this review, we focus on RM and spectroastrometry observational signatures of CB-SMBHs with non-zero eccentricity from recent simulations with particular attention to recent developments and open issues.

scholarly journals Kinematic signatures of reverberation mapping of close binaries of supermassive black holes in active galactic nuclei

2020 ◽  
Vol 635 ◽  
pp. A1 ◽  
Author(s):  
Andjelka B. Kovačević ◽  
Jian-Min Wang ◽  
Luka Č. Popović
Keyword(s):  
Black Holes ◽  
Active Galactic Nuclei ◽  
Transfer Functions ◽  
Galactic Nuclei ◽  
Supermassive Black Holes ◽  
Close Binary ◽  
Broad Line ◽  
Line Profiles ◽  
Reverberation Mapping ◽  
Line Shapes

Context. An unresolved region in the relative vicinity of the event horizon of a supermassive black holes (SMBH) in active galactic nuclei (AGN) radiates strongly variable optical continuum and broad-line emission flux. These fluxes can be processed into two-dimensional transfer functions (2DTF) of material flows that encrypt various information about these unresolved structures. An intense search for kinematic signatures of reverberation mapping of close binary SMBH (SMBBH) is currently ongoing. Aims. Elliptical SMBBH systems (i.e. both orbits and disc-like broad-line regions (BLR) are elliptic) have not been assessed in 2DTF studies. We aim to numerically infer such a 2DTF because the geometry of the unresolved region is imprinted on their optical emission. Through this, we determine their specific kinematical signatures. Methods. We simulated the geometry and kinematics of SMBBH whose components are on elliptical orbits. Each SMBH had a disc-like elliptical BLR. The SMBHs were active and orbited each other tightly at a subparsec distance. Results. Here we calculate for the first time 2DTF, as defined in the velocity-time delay plane, for several elliptical configurations of SMBBH orbits and their BLRs. We find that these very complex configurations are clearly resolved in maps. These results are distinct from those obtained from circular and disc-wind geometry. We calculate the expected line variability for all SMBBH configurations. We show that the line shapes are influenced by the orbital phase of the SMBBH. Some line profiles resemble observed profiles, but they can also be much deformed to look like those from the disc-wind model. Conclusions. First, our results imply that using our 2DTF, we can detect and quantify kinematic signatures of elliptical SMBBH. Second, the calculated expected line profiles share some intriguing similarities with observed profiles, but also with some profiles that are synthesised in disc-wind models. To overcome the non-uniqueness of the spectral line shapes as markers of SMBBH, they must be accompanied with 2DTF.

scholarly journals Probing the elliptical orbital configuration of the close binary of supermassive black holes with differential interferometry

2020 ◽  
Vol 644 ◽  
pp. A88
Author(s):  
Andjelka B. Kovačević ◽  
Yu-Yang Songsheng ◽  
Jian-Min Wang ◽  
Luka Č. Popović
Keyword(s):  
Black Holes ◽  
Near Infrared ◽  
Orbital Motion ◽  
Supermassive Black Holes ◽  
Spectral Lines ◽  
Close Binary ◽  
Close Binaries ◽  
Large Telescope ◽  
Differential Phase ◽  
Differential Interferometry

Context. Obtaining detections of electromagnetic signatures from the close binaries of supermassive black holes (CB-SMBH) is still a great observational challenge. The Very Large Telescope Interferometer (VLTI) and the Extremely Large Telescope (ELT) will serve as a robust astrophysics suite offering the opportunity to probe the structure and dynamics of CB-SMBH at a high spectral and angular resolution. Aims. Here, we explore and illustrate the application of differential interferometry on unresolved CB-SMBH systems in elliptical orbital configurations. We also investigate certain peculiarities of interferometry signals for a single SMBH with clouds in elliptical orbital motion. Methods. Photocentre displacements between each SMBH and the regions in their disc-like broad line regions (BLR) appear as small interferometric differential phase variability. To investigate the application of interferometric phases for the detection of CB-SMBH systems, we simulated a series of differential interferometry signatures, based on our model comprising ensembles of clouds surrounding each supermassive black hole in a CB-SMBH. By setting the model to the parameters of a single SMBH with elliptical cloud motion, we also calculated a series of differential interferometry observables for this case. Results. We found various deviations from the canonical S-shape of the CB-SMBH phase profile for elliptically configured CB-SMBH systems. The amplitude and specific shape of the interferometry observables depend on the orbital configurations of the CB-SMBH system. We get distinctive results when considering anti-aligned angular momenta of cloud orbits with regard to the total CB-SMBH angular momentum. We also show that their velocity distributions differ from the aligned cloud orbital motion. Some simulated spectral lines from our model closely resemble observations from the Paα line obtained from near-infrared AGN surveys. We found differences between the “zoo” of differential phases of single SMBH and CB-SMBH systems. The “zoo” of differential phases for a single SMBH take a deformed S shape. We also show how their differential phase shape, amplitude, and slope evolve with various sets of cloud orbital parameters and the observer’s position. Conclusions. We calculate an extensive atlas of the interferometric observables, revealing distinctive signatures for the elliptical configuration CB-SMBH. We also provide an interferometry atlas for the case of a single SMBH with clouds with an elliptical motion, which differs from those of a CB-SMBH. These maps can be useful for extracting exceptional features of the BLR structure from future high-resolution observations of CB-SMBH systems, but also of a single SMBH with clouds in an elliptical orbital setup.

scholarly journals Epicyclic Oscillations around Simpson–Visser Regular Black Holes and Wormholes

Universe ◽  
2021 ◽  
Vol 7 (8) ◽  
pp. 279
Author(s):  
Zdeněk Stuchlík ◽  
Jaroslav Vrba
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Active Galactic Nuclei ◽  
Observational Data ◽  
High Frequency ◽  
Galactic Nuclei ◽  
Supermassive Black Holes ◽  
Periodic Oscillations ◽  
High Length ◽  
Circular Geodesic

We study epicyclic oscillatory motion along circular geodesics of the Simpson–Visser meta-geometry describing in a unique way regular black-bounce black holes and reflection-symmetric wormholes by using a length parameter l. We give the frequencies of the orbital and epicyclic motion in a Keplerian disc with inner edge at the innermost circular geodesic located above the black hole outer horizon or on the our side of the wormhole. We use these frequencies in the epicyclic resonance version of the so-called geodesic models of high-frequency quasi-periodic oscillations (HF QPOs) observed in microquasars and around supermassive black holes in active galactic nuclei to test the ability of this meta-geometry to improve the fitting of HF QPOs observational data from the surrounding of supermassive black holes. We demonstrate that this is really possible for wormholes with sufficiently high length parameter l.

scholarly journals Cosmological Evolution of Supermassive Black Holes: Mass Functions and Spins

2012 ◽  
Vol 8 (S290) ◽  
pp. 259-260 ◽  
Author(s):  
Yan-Rong Li ◽  
Jian-Min Wang ◽  
Luis C. Ho
Keyword(s):  
Black Holes ◽  
Mass Function ◽  
Supermassive Black Holes ◽  
Cosmological Evolution ◽  
Radiative Efficiency ◽  
Bolometric Luminosity ◽  
History Of ◽  
Minor Mergers ◽  
Mass Dependent ◽  
Mass Functions

AbstractWe derive the mass function of supermassive black holes (SMBHs) over the redshift range 0 > z ≲ 2, using the latest deep luminosity and mass functions of field galaxies. Applying this mass function, combined with the bolometric luminosity function of active galactic nuclei (AGNs), into the the continuity equation of SMBH number density, we explicitly obtain the mass-dependent cosmological evolution of the radiative efficiency for accretion. We suggest that the accretion history of SMBHs and their spins evolve in two distinct regimes: an early phase of prolonged accretion, plausibly driven by major mergers, during which the black hole spins up, then switching to a period of random, episodic accretion, governed by minor mergers and internal secular processes, during which the hole spins down. The transition epoch depends on mass, mirroring other evidence for “cosmic downsizing” in the AGN population.

scholarly journals The ecology of the galactic centre: Nuclear stellar clusters and supermassive black holes

2019 ◽  
Vol 14 (S351) ◽  
pp. 80-83 ◽  
Author(s):  
Melvyn B. Davies ◽  
Abbas Askar ◽  
Ross P. Church
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Large Fraction ◽  
Galactic Nuclei ◽  
Supermassive Black Holes ◽  
Galactic Centre ◽  
Stellar Clusters ◽  
Stellar Cluster ◽  
Supermassive Black Hole ◽  
Multiple Clusters

AbstractSupermassive black holes are found in most galactic nuclei. A large fraction of these nuclei also contain a nuclear stellar cluster surrounding the black hole. Here we consider the idea that the nuclear stellar cluster formed first and that the supermassive black hole grew later. In particular we consider the merger of three stellar clusters to form a nuclear stellar cluster, where some of these clusters contain a single intermediate-mass black hole (IMBH). In the cases where multiple clusters contain IMBHs, we discuss whether the black holes are likely to merge and whether such mergers are likely to result in the ejection of the merged black hole from the nuclear stellar cluster. In some cases, no supermassive black hole will form as any merger product is not retained. This is a natural pathway to explain those galactic nuclei that contain a nuclear stellar cluster but apparently lack a supermassive black hole; M33 being a nearby example. Alternatively, if an IMBH merger product is retained within the nuclear stellar cluster, it may subsequently grow, e.g. via the tidal disruption of stars, to form a supermassive black hole.

scholarly journals Composite profile of the Fe Kα spectral line emitted from a binary system of supermassive black holes

2014 ◽  
Vol 54 (7) ◽  
pp. 1448-1457 ◽  
Author(s):  
P. Jovanović ◽  
V. Borka Jovanović ◽  
D. Borka ◽  
T. Bogdanović
Keyword(s):  
Black Holes ◽  
Binary System ◽  
Spectral Line ◽  
Supermassive Black Holes

scholarly journals Finding Local Low-mass Supermassive Black Holes

2008 ◽  
Author(s):  
Smita Mathur ◽  
Himel Ghosh ◽  
Laura Ferrarese ◽  
Fabrizio Fiore ◽  
Sandip K. Chakrabarti ◽  
...  
Keyword(s):  
Black Holes ◽  
Supermassive Black Holes ◽  
Low Mass
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