Symmetry and the Arrow of Time in Theoretical Black Hole Astrophysics

While the basic laws of physics seem time-reversal invariant, our understanding of the apparent irreversibility of the macroscopic world is well grounded in the notion of entropy. Because astrophysics deals with the largest structures in the Universe, one expects evidence there for the most pronounced entropic arrow of time. However, in recent theoretical astrophysics work it appears possible to identify constructs with time-reversal symmetry, which is puzzling in the large-scale realm especially because it involves the engines of powerful outflows in active galactic nuclei which deal with macroscopic constituents such as accretion disks, magnetic fields, and black holes. Nonetheless, the underlying theoretical structure from which this accreting black hole framework emerges displays a time-symmetric harmonic behavior, a feature reminiscent of basic and simple laws of physics. While we may expect such behavior for classical black holes due to their simplicity, manifestations of such symmetry on the scale of galaxies, instead, surprise. In fact, we identify a parallel between the astrophysical tug-of-war between accretion disks and jets in this model and the time symmetry-breaking of a simple overdamped harmonic oscillator. The validity of these theoretical ideas in combination with this unexpected parallel suggests that black holes are more influential in astrophysics than currently recognized and that black hole astrophysics is a more fundamental discipline.

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Influence of Black Hole Spin on the Shape of the Fe Kα Spectral Line: The Case of 3C 405

Open Astronomy ◽

10.1515/astro-2017-0321 ◽

2011 ◽

Vol 20 (3) ◽

Author(s):

P. Jovanović ◽

V. Borka Jovanović ◽

D. Borka

Keyword(s):

Black Holes ◽

Black Hole ◽

Active Galactic Nuclei ◽

Accretion Disks ◽

Galactic Nuclei ◽

Kerr Metric ◽

Line Shapes ◽

Cygnus A ◽

Angular Momenta ◽

Innermost Region

AbstractHere we analyze how the angular momenta (spins) of black holes in the centers of Active Galactic Nuclei (AGN) affect the shape of the FeK line emitted from their accretion disks. For that purpose, we compared the observed line profile in the case of radio galaxy 3C 405 (Cygnus A) with its profiles, obtained by numerical simulations based on ray-tracing method in the Kerr metric. Our results show that the spins of rotating central black holes of AGN have significant influence on their FeKα line shapes. Also, we found that in the case of Cygnus A the observed line is probably emitted from the innermost region of its slightly inclined accretion disk around very slowly rotating or even stationary central black hole.

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Large-scale dynamo of accretion disks around supermassive nonrotating black holes

Serbian Astronomical Journal ◽

10.2298/saj0673049p ◽

2006 ◽

pp. 49-55

Author(s):

A.L. Poplavsky ◽

O.P. Kuznechik ◽

N.I. Stetyukevich

Keyword(s):

Magnetic Field ◽

Black Holes ◽

Active Galactic Nuclei ◽

Accretion Disks ◽

Large Scale ◽

Temporal Distribution ◽

Galactic Nuclei ◽

Dynamo Action ◽

Stable Circular Orbit ◽

General Relativistic

In this paper one presents an analytical model of accretion disk magnetosphere dynamics around supermassive nonrotating black holes in the centers of active galactic nuclei. Based on general relativistic equations of magneto hydrodynamics, the nonstationary solutions for time-dependent dynamo action in the accretion disks, spatial and temporal distribution of magnetic field are found. It is shown that there are two distinct stages of dynamo process: the transient and the steady-state regimes, the induction of magnetic field at t > 6:6665 x 1011GM/c3 s becomes stationary, magnetic field is located near the innermost stable circular orbit, and its value rises up to ~ 105 G. Applications of such systems with nonrotating black holes in real active galactic nuclei are discussed.

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Sweeping-Magnetic-Twist Mechanism and Molecular Bipolar Flows

Symposium - International Astronomical Union ◽

10.1017/s0074180900096029 ◽

1987 ◽

Vol 115 ◽

pp. 385-387

Author(s):

Kazunari SHIBATA ◽

Yutaka UCHIDA

Keyword(s):

Magnetic Field ◽

Black Hole ◽

Active Galactic Nuclei ◽

Accretion Disks ◽

Large Scale ◽

Galactic Nuclei ◽

Main Mechanism ◽

Astrophysical Jets ◽

Centrifugal Effect ◽

Poloidal Magnetic Field

Uchida and Shibata have proposed the “sweeping-magnetic-twist” mechanism for the formation of astrophysical jets in relation to the accretion disks (disks around protostars, around black hole in the center of active galactic nuclei, and so on) in which a jet is accelerated by thejxBforce in the relaxing magnetic twist created in the winding-up of the poloidal magnetic field by the rotation of the contracting disk (Uchida and Shibata 1985a, b; Shibata and Uchida 1986a, b; Uchidaet al.1985). In this mechanism, a jet is collimated also by thejxBforce due to the large scale poloidal magnetic field whose footpoints are squeezed in the contracting disk. The main mechanism involved is different from that of centrifugal wind models (Blandford and Payne 1982, Pudritz and Norman 1983) and worked out indepentently, but the centrifugal effect itself is automatically built-in.

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Slow and massive: low-spin SMBHs can grow more

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz2235 ◽

2019 ◽

Vol 489 (1) ◽

pp. 1373-1378 ◽

Cited By ~ 1

Author(s):

Kastytis Zubovas ◽

Andrew King

Keyword(s):

Black Holes ◽

Black Hole ◽

Active Galactic Nuclei ◽

Large Scale ◽

Size Dependence ◽

Galactic Nuclei ◽

Host Galaxy ◽

Host Galaxies ◽

The Galaxy ◽

Mass Increment

Abstract Active galactic nuclei (AGNs) probably control the growth of their host galaxies via feedback in the form of wide-angle wind-driven outflows. These establish the observed correlations between supermassive black hole (SMBH) masses and host galaxy properties, e.g. the spheroid velocity dispersion σ. In this paper we consider the growth of the SMBH once it starts driving a large-scale outflow through the galaxy. To clear the gas and ultimately terminate further growth of both the SMBH and the host galaxy, the black hole must continue to grow its mass significantly, by up to a factor of a few, after reaching this point. The mass increment ΔMBH depends sensitively on both galaxy size and SMBH spin. The galaxy size dependence leads to ΔMBH ∝ σ5 and a steepening of the M–σ relation beyond the analytically calculated M ∝ σ4, in agreement with observation. Slowly spinning black holes are much less efficient in producing feedback, so at any given σ the slowest spinning black holes should be the most massive. Current observational constraints are consistent with this picture, but insufficient to test it properly; however, this should change with upcoming surveys.

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A TWO-STEP MECHANISM FOR PARTICLE ACCELERATION IN THE MAGNETOSPHERE OF ACCRETING BLACK HOLES

International Journal of Modern Physics D ◽

10.1142/s0218271808013182 ◽

2008 ◽

Vol 17 (09) ◽

pp. 1585-1590

Author(s):

YA. ISTOMIN ◽

H. SOL

Keyword(s):

Black Holes ◽

Black Hole ◽

Active Galactic Nuclei ◽

Accretion Disks ◽

Gamma Rays ◽

Galactic Nuclei ◽

Massive Black Holes ◽

Relativistic Beaming ◽

Ejection Process ◽

Step Mechanism

Fast variability now observed in VHE gamma-rays from active galactic nuclei (PKS 2155–304, M87, Mkn 501) seems to require very small TeV emitting zones, even in the presence of a significant relativistic beaming. We explore the possibility to accelerate particles up to VHE energies in such small compact regions around massive black holes, taking into account the two places in the black hole surroundings where efficient acceleration can be expected during the accretion-ejection process, namely turbulent low-luminosity accretion disks and rotating magnetospheres.

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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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Gaseous Disks in the Nuclei of Elliptical Galaxies

International Astronomical Union Colloquium ◽

10.1017/s0252921100043293 ◽

1997 ◽

Vol 163 ◽

pp. 620-625 ◽

Cited By ~ 4

Author(s):

H. Ford ◽

Z. Tsvetanov ◽

L. Ferrarese ◽

G. Kriss ◽

W. Jaffe ◽

...

Keyword(s):

Black Holes ◽

Black Hole ◽

Angular Momentum ◽

Accretion Disks ◽

Large Scale ◽

Elliptical Galaxies ◽

Central Mass ◽

Massive Black Holes ◽

Radio Jets

AbstractHST images have led to the discovery that small (r ~ 1″ r ~ 100 – 200 pc), well-defined, gaseous disks are common in the nuclei of elliptical galaxies. Measurements of rotational velocities in the disks provide a means to measure the central mass and search for massive black holes in the parent galaxies. The minor axes of these disks are closely aligned with the directions of the large–scale radio jets, suggesting that it is angular momentum of the disk rather than that of the black hole that determines the direction of the radio jets. Because the disks are directly observable, we can study the disks themselves, and investigate important questions which cannot be directly addressed with observations of the smaller and unresolved central accretion disks. In this paper we summarize what has been learned to date in this rapidly unfolding new field.

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Supermassive black holes surrounded by dark matter modeled as anisotropic fluid: epicyclic oscillations and their fitting to observed QPOs

Journal of Cosmology and Astroparticle Physics ◽

10.1088/1475-7516/2021/11/059 ◽

2021 ◽

Vol 2021 (11) ◽

pp. 059

Author(s):

Z. Stuchlík ◽

J. Vrba

Keyword(s):

Black Holes ◽

Black Hole ◽

Dark Matter ◽

Active Galactic Nuclei ◽

Galactic Nuclei ◽

Supermassive Black Holes ◽

Anisotropic Fluid ◽

Physical Parameters ◽

Black Hole Spacetimes ◽

Test Particles

Abstract Recently introduced exact solution of the Einstein gravity coupled minimally to an anisotropic fluid representing dark matter can well represent supermassive black holes in galactic nuclei with realistic distribution of dark matter around the black hole, given by the Hernquist-like density distribution. For these fluid-hairy black hole spacetimes, properties of the gravitational radiation, quasinormal ringing, and optical phenomena were studied, giving interesting results. Here, using the range of physical parameters of these spacetimes allowing for their relevance in astrophysics, we study the epicyclic oscillatory motion of test particles in these spacetimes. The frequencies of the orbital and epicyclic motion are applied in the epicyclic resonance variant of the geodesic model of quasiperiodic oscillations (QPOs) observed in active galactic nuclei to demonstrate the possibility to solve the cases where the standard vacuum black hole spacetimes are not allowing for explanation of the observed data. We demonstrate that the geodesic model can explain the QPOs observed in most of the active galactic nuclei for the fluid-hairy black holes with reasonable halo parameters.

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Numerical Studies of Astrophysical Objects at Fesenkov Astrophysical Institute (FAI)

Communications of the Byurakan Astrophysical Observatory ◽

10.52526/25792776-2018.2.1-124 ◽

2018 ◽

Vol 2 (1) ◽

pp. 124-134

Author(s):

Assylkhan Bibossinov ◽

◽

Denis Yurin ◽

Chingis Omarov ◽

◽

...

Keyword(s):

Black Hole ◽

Numerical Simulations ◽

Active Galactic Nuclei ◽

Accretion Disk ◽

Large Scale ◽

International Workshop ◽

Star Clusters ◽

Galactic Nuclei ◽

Numerical Studies ◽

Astrophysical Objects

Numerical studies of astrophysical objects are a relatively new direction in Fesenkov Astrophysical Institute (FAI) and is mainly represented by the Laboratory of Cosmology, Stellar Dynamics and Computational Astrophysics. The lab seeks to understand the evolution of gravitating systems at various scales – from star clusters to galaxies to large-scale structure of the universe as a whole, and tackles these problems both through analytical methods and through numerical simulations. The particular focus is on numerical simulations of star clusters, especially those found in active galactic nuclei – this is a topic of oldestablished collaboration with colleagues from Astronomisches Rechen-Institut (Heidelberg) and National Astronomical Observatories of China (Beijing). The prominent example is STARDISK project dedicated to the numerical research of active galactic nuclei as multicomponent systems composed of compact stellar cluster, gaseous accretion disk and a supermassive black hole. It is demonstrated that an accretion disk can noticeably decelerate stars and thus enhance the accretion rate onto the black hole. In 2013 FAI hosted the MODEST-13 International Workshop dedicated to modeling of star clusters. Recently a new project has been approved aimed at construction of triaxial equilibrium N-body systems that can be of great help in various numerical experiments with disk galaxies. There are also long standing plans to perform cosmological simulations of large scale structures to test a new approach to dark matter and energy actively developed at FAI. For numerical calculations, FAI has a small, but growing computer cluster consisting of several high-performance computing servers equipped with computational GPU cards.

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