Ratio of kinetic-to-bolometric luminosity at the “cold” disk accretion onto black holes

Disk accretion onto black holes is accompanied by collimated outflows (jets). In active galactic nuclei (AGN), the kinetic energy flux of the jet (jet power or kinetic luminosity) may exceed the bolometric luminosity of the disk by a few orders of magnitude. This may be explained in the framework of the so-called “cold” disk accretion when the only source of the AGN energy is the energy released by accretion. The radiation from the disk is suppressed because the disk wind carries out almost all the angular momentum and the gravitational energy of the accreting material. In this paper, we calculate the “unavoidable” radiation from the “cold” disk and the ratio of the kinetic energy power of the outflow to the bolometric luminosity of the accretion disk around a super massive black hole in the framework of the Shakura and Sunyaev paradigm of an optically thick [Formula: see text]-disk. The exploration of the Fundamental Plane of Black Holes allows us to obtain equations that define the bolometric luminosity and the ratio of the luminosities as functions of the black hole mass and accretion rate. The application of our equations in the case of the M87 jet demonstrates good agreement with observations. In the case of Sgr A*, these equations allow us to predict the kinetic energy flux from the disk around the Galactic supermassive black hole.

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Physics of “Cold” Disk Accretion onto Black Holes Driven by Magnetized Winds

Galaxies ◽

10.3390/galaxies7010018 ◽

2019 ◽

Vol 7 (1) ◽

pp. 18 ◽

Cited By ~ 1

Author(s):

Sergey Bogovalov

Keyword(s):

Black Holes ◽

Black Hole ◽

Angular Momentum ◽

Numerical Solutions ◽

Turbulent Viscosity ◽

Disk Accretion ◽

Massive Black Hole ◽

Bolometric Luminosity ◽

Semi Empirical ◽

Jet Power

Disk accretion onto black holes is accompanied by collimated outflows (jets). In active galactic nuclei (AGN), the kinetic energy flux of the jet (jet power or kinetic luminosity) may exceed the bolometric luminosity of the disk by a few orders of magnitude. This may be explained in the framework of the so called “cold” disk accretion. In this regime of accretion, the disk is radiatively inefficient because practically all the energy released at the accretion is carried out by the magnetized wind. This wind also provides efficient loss of the angular momentum by the matter in the disk. In this review, the physics of the accretion driven by the wind is considered from first principles. It is shown that the magnetized wind can efficiently carry out angular momentum and energy of the matter of the disk. The conditions when this process dominates conventional loss of the angular momentum due to turbulent viscosity are discussed. The “cold” accretion occurs when the viscous stresses in the disk can be neglected in comparison with impact of the wind on the accretion. Two problems crucial for survival of the model of “cold” accretion are considered. The first one is existence of the magnetohydrodynamical solutions for disk accretion purely due to the angular momentum loss by the wind. Another problem is the ability of the model to reproduce observations which demonstrate existence of the sources with kinetic power of jets 2–3 orders of magnitude exceeding the bolometric luminosity of disks. The solutions of the problem in similar prescriptions and numerical solutions without such an assumption are discussed. Calculations of the “unavoidable” radiation from the “cold” disk and the ratio of the jet power of the SMBH to the bolometric luminosity of the accretion disk around a super massive black hole are given in the framework of the Shakura and Sunyaev paradigm of an optically thick α -disk. The exploration of the Fundamental Plane of Black Holes allows us to obtain semi empirical equations that determine the bolometric luminosity and the ratio of the luminosities as functions of the black hole mass and accretion rate.

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Active Galactic Nuclei: Variability at Many Wavelengths

Highlights of Astronomy ◽

10.1017/s1539299600018840 ◽

1998 ◽

Vol 11 (2) ◽

pp. 808-811

Author(s):

Thierry J.-L. Courvoisier

Keyword(s):

Black Hole ◽

Active Galactic Nuclei ◽

Thermal Emission ◽

Galactic Nuclei ◽

Gravitational Energy ◽

Heating Process ◽

Massive Black Hole ◽

Ultraviolet Emission ◽

X Ray ◽

Accretion Process

Active Galactic Nuclei (AGN) are thought to be powered by accretion onto a massive black hole. Understanding how gravitational energy freed by the infall of matter into the black hole is transferred to the radiating regions of the nucleus is one of the main challenges of AGN research. The question is made very complex by the presence of several cooling mechanisms with very diverse physical properties: We observe synchrotron radiation, thermal emission from hot dust, possibly thermal optical and ultraviolet emission and Comptonization processes in the X-ray domain. For each component the radiation is a signature of the cooling process rather than of the heating process. It is our hope that by observing the links and correlations between the emission of the different components we will be able to understand how they are interrelated and how they get their energy supply from the accretion process.

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Black Hole Models of Quasars

Symposium - International Astronomical Union ◽

10.1017/s0074180900153021 ◽

1986 ◽

Vol 119 ◽

pp. 359-369 ◽

Cited By ~ 2

Author(s):

R. D. Blandford

Keyword(s):

Black Holes ◽

Black Hole ◽

Active Galactic Nuclei ◽

Cosmic Time ◽

Galactic Nuclei ◽

Seyfert Galaxies ◽

Massive Black Hole ◽

Binary Black Holes ◽

Electron Positron ◽

Gas Supply

Observations of active galactic nuclei are interpreted in terms of a theoretical model involving accretion onto a massive black hole. Optical quasars and Seyfert galaxies are associated with holes accreting near the Eddington rate and radio galaxies with sub-critical accretion. It is argued that magnetic fields are largely responsible for extracting energy and angular momentum from black holes and disks. Recent studies of electron-positron pair plasmas and their possible role in establishing the emergent X-ray spectrum are reviewed. The main evolutionary properties of active galactic nuclei can be interpreted in terms of a simple model in which black holes accrete gas at a rate dictated by the rate of gas supply which decreases with cosmic time. It may be worth searching for eclipsing binary black holes in lower power Seyferts.

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Toward the self-consistent model of cold disk accretion

International Journal of Modern Physics D ◽

10.1142/s0218271818440054 ◽

2018 ◽

Vol 27 (10) ◽

pp. 1844005 ◽

Cited By ~ 1

Author(s):

S. V. Bogovalov ◽

I. V. Tronin

Keyword(s):

Angular Momentum ◽

Galactic Nuclei ◽

Disk Accretion ◽

Mass Rate ◽

Bolometric Luminosity ◽

Consistent Model ◽

Self Consistent ◽

Angular Momentum Loss ◽

Consistent Solution ◽

Viscous Stresses

Observations of active galactic nuclei show increasing number of cases when the kinetic luminosity of jets exceeds the bolometric luminosity of disks. We develop a model of so-called cold disk accretion when the majority of the angular momentum is carried out by the wind from the disk rather than by turbulent viscous stresses. In this case the luminosity of the disk can be essentially suppressed and kinetic-to-bolometric luminosity ratio can be consistent with the observations. The method of self-consistent numerical solution of the problem of the outflow and disk accretion is proposed in this work. In this problem the angular momentum carried out by the wind is equal to the angular momentum loss by the Keplerian disk with specified accretion mass rate. Thus, the problem of the wind outflow is consistent with the disk accretion. Example of self-consistent solution of the problem by this method is presented.

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11.14. Massive black hole binaries in galactic nuclei

Symposium - International Astronomical Union ◽

10.1017/s0074180900085685 ◽

1998 ◽

Vol 184 ◽

pp. 483-484

Author(s):

Junichiro Makino

Keyword(s):

Black Holes ◽

Black Hole ◽

Density Distribution ◽

Velocity Dispersion ◽

Galactic Nuclei ◽

Effective Radius ◽

Central Density ◽

Massive Black Hole ◽

Black Hole Binaries

Many large ellipticals were believed to have large, flat core, of which the radius is typically a few percents of the effective radius (e.g., Lauer, 1985). However, HST observations (e.g., Lauer et al., 1995) have revealed that they are not flat cores at all. The “cores” observed by HST are actually very shallow central density cusps (ρ ~ r−0.5~–1). Such a shallow cusp poses a serious problem to almost any scenario of the formation of ellipticals. If these ellipticals do not have central black holes (MBHs), we are faced with very strange structure with the velocity dispersion decreasing inward. Neither dissipationless/dissipational collapse nor merging have been able to make such a density distribution.

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Merging of unequal mass binary black holes in non-axisymmetric galactic nuclei

Proceedings of the International Astronomical Union ◽

10.1017/s1743921315007577 ◽

2014 ◽

Vol 10 (S312) ◽

pp. 82-85

Author(s):

Peter Berczik ◽

Long Wang ◽

Keigo Nitadori ◽

Rainer Spurzem

Keyword(s):

Black Holes ◽

Black Hole ◽

Galactic Nuclei ◽

Hardware Acceleration ◽

Galaxy Mergers ◽

Mass Ratio ◽

Graphic Processing Units ◽

Massive Black Hole ◽

Binary Black Holes ◽

Unequal Mass

AbstractIn this work we study the stellar-dynamical hardening of unequal mass massive black hole (MBH) binaries in the central regions of galactic nuclei. We present a comprehensive set of direct N-body simulations of the problem, varying both the total mass and the mass ratio of the MBH binary. Our initial model starts as an axisymmetric, rotating galactic nucleus, to describe the situation right after the galaxies have merged, but the black holes are still unbound to each other. We confirm that results presented in earlier works (Berczik et al. 2006; Khan et al. 2013; Wang et al. 2014) about the solution of the “last parsec problem” (sufficiently fast black hole coalescence for black hole growth in cosmological context) are robust for both for the case of unequal black hole masses and large particle numbers. The MBH binary hardening rate depends on the reduced mass ratio through a single parameter function, which quantitatively quite well agrees with standard 3 body scattering theory (see e.g., Hills 1983). Based on our results we conclude that MBH binaries at high redshifts are expected to merge with a factor of ~ 2 more efficiently, which is important to determine the possible overall gravitational wave signals. However, we have not yet fully covered all the possible parameter space, in particular with respect to the preceding of the galaxy mergers, which may lead to a wider variety of initial models, such as initially more oblate and / or even significantly triaxial galactic nuclei. Our N-body simulations were carried out on a new special supercomputers using the hardware acceleration with graphic processing units (GPUs).

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8.12. MHD accretion in a black hole magnetosphere

Symposium - International Astronomical Union ◽

10.1017/s0074180900085259 ◽

1998 ◽

Vol 184 ◽

pp. 367-368

Author(s):

M. Takahashi

Keyword(s):

Black Hole ◽

Active Galactic Nuclei ◽

Thermal Effects ◽

Galactic Nuclei ◽

Plasma Source ◽

Gravitational Energy ◽

Massive Black Hole ◽

Plasma Sources ◽

Strong Gravitation ◽

The Ideal

To explain the activity of active galactic nuclei or compact X-ray sources, I consider a black hole magnetosphere in the center of these objects. The considering black hole magnetosphere is composed of a massive black hole with surrounding fluids and magnetic fields, and rotates rapidly. Because of the strong gravitation and the rapid rotation, both an accretion and a wind/jet would be generated from plasma sources (e.g., an accretion disk and its corona). The outgoing flow carries the angular momentum from the plasma source effectively, and then the accretion would go on stationary, releasing its gravitational energy. I assume that the magnetosphere is stationary and axisymmetric, and that the ideal MHD approximation is available for the streaming fluid. I discuss the thermal effects on MHD flows, and then I argue that the trans-fast MHD accretion solution can be broken by highly thermal effects.

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Epicyclic Oscillations around Simpson–Visser Regular Black Holes and Wormholes

Universe ◽

10.3390/universe7080279 ◽

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.

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

Proceedings of the International Astronomical Union ◽

10.1017/s1743921319006689 ◽

2019 ◽

Vol 14 (S351) ◽

pp. 80-83 ◽

Cited By ~ 1

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.

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