scholarly journals Probing the accretion disk - jet connection via instabilities in the inner accretion flow. From microquasars to quasars

2010 ◽  
Vol 6 (S275) ◽  
pp. 94-95
Author(s):  
Agnieszka Janiuk ◽  
Bożena Czerny ◽  
Monika Mościbrodzka ◽  
Aneta Siemiginowska
Keyword(s):  
Black Hole ◽  
Accretion Disk ◽  
Radiation Pressure ◽  
Duty Cycle ◽  
Thermal Instability ◽  
Accretion Flow ◽  
Supermassive Black Hole ◽  
Complex Morphology ◽  
Hydrogen Ionization ◽  
Jet Axis

AbstractWe present various instability mechanisms in the accreting black hole systems which might indicate at the connection between the accretion disk and jet. The jets observed in microquasars can have a peristent or blobby morphology. Correlated with the accretion luminosity, this might provide a link to the cyclic outbursts of the disk. Such duty-cycle type of behaviour on short timescales results from the thermal instability caused by the radiation pressure domination. The same type of instability may explain the cyclic radioactivity of the supermassive black hole systems. The somewhat longer timescales are characteristic for the instability caused by the partial hydrogen ionization. The distortions of the jet direction and complex morphology of the sources can be caused by precession of the disk-jet axis.

scholarly journals Intermittent activity of radio sources. Accretion instabilities and jet precession.

2010 ◽  
Vol 6 (S275) ◽  
pp. 180-181 ◽  
Author(s):  
M. Kunert-Bajraszewska ◽  
A. Janiuk ◽  
A. Siemiginowska ◽  
M. Gawroński
Keyword(s):  
Black Hole ◽  
Accretion Disk ◽  
Radiation Pressure ◽  
Hot Spots ◽  
Radio Sources ◽  
Supermassive Black Hole ◽  
Complex Morphology ◽  
Vlbi Observations ◽  
Intermittent Activity ◽  
Propagation Velocities

AbstractWe consider the radiation pressure instability operating on short timescales (103 - 106 years) in the accretion disk around a supermassive black hole as the origin of the intermittent activity of radio sources. We test whether this instability can be responsible for short ages (<104 years) of Compact Steep Spectrum sources measured by hot spots propagation velocities in VLBI observations and statistical overabundance of Gigahertz Peaked Spectrum sources. The implied timescales are consistent with the observed ages of the sources. We aslo discuss possible implications of the intermittent activity on the complex morphology of radio sources, such as the quasar 1045+352, dominated by a knotty jet showing several bends. It is possible that we are whitnessing an ongoing jet precession in this source due to internal instabilities within the jet flow.

The inner edge of the accretion disk around a supermassive black hole

Nature ◽  
10.1038/34130 ◽  
1998 ◽  
Vol 391 (6662) ◽  
pp. 54-56 ◽  
Author(s):  
B. C. Bromley ◽  
W. A. Miller ◽  
V. I. Pariev
Keyword(s):  
Black Hole ◽  
Accretion Disk ◽  
Supermassive Black Hole

Radio continuum of galaxies with H2O megamaser disks

2017 ◽  
Vol 13 (S336) ◽  
pp. 139-140
Author(s):  
F. Kamali ◽  
C. Henkel ◽  
A. Brunthaler ◽  
C. M. V. Impellizzeri ◽  
K. M. Menten ◽  
...  
Keyword(s):  
Black Hole ◽  
Accretion Disk ◽  
Active Galactic Nucleus ◽  
Position Angle ◽  
Radio Continuum ◽  
Supermassive Black Hole ◽  
5 Ghz

AbstractIn our attempt to investigate the basic active galactic nucleus (AGN) paradigm requiring a centrally located supermassive black hole (SMBH), a close to Keplerian accretion disk and a jet perpendicular to its plane, we have searched for radio continuum in galaxies with H2O megamasers in their disks. We observed 18 such galaxies with the Very Large Baseline Array in C band (5 GHz, ~2 mas resolution) and we detected 5 galaxies at 8 σ or higher levels. For those sources for which the maser data is available, the positions of masers and those of the 5 GHz radio continuum sources coincide within the uncertainties, and the radio continuum is perpendicular to the maser disk’s orientation within the position angle uncertainties.

2.9. Microlens mapping of disks in active galactic nuclei

1998 ◽  
Vol 184 ◽  
pp. 75-76 ◽  
Author(s):  
A. Yonehara ◽  
S. Mineshige ◽  
J. Fukue ◽  
M. Umemura ◽  
E.L. Turner
Keyword(s):  
Black Hole ◽  
Active Galactic Nuclei ◽  
Accretion Disk ◽  
Central Region ◽  
Galactic Nuclei ◽  
Direct Information ◽  
Supermassive Black Hole ◽  
Disk Size

Generally, it is believed that there is a supermassive black hole and a surrounding accretion disk in a central region of active galactic nuclei (AGN). However, it is quite difficult to obtain direct information about the center of AGN, because the accretion disk size is far too small to resolve.

scholarly journals Warm and thick corona for a magnetically supported disk in galactic black hole binaries

2020 ◽  
Vol 633 ◽  
pp. A35 ◽  
Author(s):  
D. Gronkiewicz ◽  
A. Różańska
Keyword(s):  
Magnetic Field ◽  
Black Hole ◽  
Accretion Disk ◽  
Thermal Instability ◽  
Stellar Mass ◽  
Rotational Instability ◽  
X Ray ◽  
Black Hole Binaries ◽  
Radiative Processes ◽  
Gas Heating

Context. We self-consistently model a magnetically supported accretion disk around a stellar-mass black hole with a warm optically thick corona based on first principles. We consider the gas heating by magneto-rotational instability dynamo. Aims. Our goal is to show that the proper calculation of the gas heating by magnetic dynamo can build up the warm optically thick corona above the accretion disk around a black hole of stellar mass. Methods. Using the vertical model of the disk supported and heated by the magnetic field together with radiative transfer in hydrostatic and radiative equilibrium, we developed a relaxation numerical scheme that allowed us to compute the transition form the disk to corona in a self-consistent way. Results. We demonstrate here that the warm (up to 5 keV) optically thick (up to 10 τes) Compton-cooled corona can form as a result of magnetic heating. A warm corona like this is stronger in the case of the higher accretion rate and the greater magnetic field strength. The radial extent of the warm corona is limited by local thermal instability, which purely depends on radiative processes. The obtained coronal parameters are in agreement with those constrained from X-ray observations. Conclusions. A warm magnetically supported corona tends to appear in the inner disk regions. It may be responsible for soft X-ray excess seen in accreting sources. For lower accretion rates and weaker magnetic field parameters, thermal instability prevents a warm corona, giving rise to eventual clumpiness or ionized outflow.

Determination of supermassive black hole spins in active galactic nuclei

2020 ◽  
Vol 35 (02n03) ◽  
pp. 2040054
Author(s):  
M. Yu. Piotrovich ◽  
V. L. Afanasiev ◽  
S. D. Buliga ◽  
T. M. Natsvlishvili
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Active Galactic Nuclei ◽  
Accretion Disk ◽  
Galactic Nuclei ◽  
Supermassive Black Holes ◽  
Disk Model ◽  
Supermassive Black Hole

Based on spectropolarimetry for a number of active galactic nuclei in Seyfert 1 type galaxies observed with the 6-m BTA telescope, we have estimated the spins of the supermassive black holes at the centers of these galaxies. We have determined the spins based on the standard Shakura-Sunyaev accretion disk model. More than 70% of the investigated active galactic nuclei are shown to have Kerr supermassive black holes with a dimensionless spin greater than 0.9.

scholarly journals RESOLVING THE BONDI ACCRETION FLOW TOWARD THE SUPERMASSIVE BLACK HOLE OF NGC 3115 WITH CHANDRA

2011 ◽  
Vol 736 (1) ◽  
pp. L23 ◽  
Author(s):  
Ka-Wah Wong ◽  
Jimmy A. Irwin ◽  
Mihoko Yukita ◽  
Evan T. Million ◽  
William G. Mathews ◽  
...  
Keyword(s):  
Black Hole ◽  
Accretion Flow ◽  
Supermassive Black Hole

scholarly journals The Brightest Point in Accretion Disk and Black Hole Spin: Implication to the Image of Black Hole M87*

Universe ◽  
2019 ◽  
Vol 5 (8) ◽  
pp. 183 ◽  
Author(s):  
Vyacheslav I. Dokuchaev ◽  
Natalia O. Nazarova
Keyword(s):  
Black Hole ◽  
Event Horizon ◽  
Accretion Disk ◽  
Disk Model ◽  
Dark Region ◽  
High Resolution Image ◽  
Supermassive Black Hole ◽  
Black Hole Spin ◽  
The Galaxy ◽  
Expected Position

We propose the simple new method for extracting the value of the black hole spin from the direct high-resolution image of black hole by using a thin accretion disk model. In this model, the observed dark region on the first image of the supermassive black hole in the galaxy M87, obtained by the Event Horizon Telescope, is a silhouette of the black hole event horizon. The outline of this silhouette is the equator of the event horizon sphere. The dark silhouette of the black hole event horizon is placed within the expected position of the black hole shadow, which is not revealed on the first image. We calculated numerically the relation between the observed position of the black hole silhouette and the brightest point in the thin accretion disk, depending on the black hole spin. From this relation, we derive the spin of the supermassive black hole M87*, a = 0.75 ± 0.15 .

scholarly journals SUPERMASSIVE BLACK HOLE BINARIES AT HIGH ENERGIES

2014 ◽  
Vol 28 ◽  
pp. 1460183
Author(s):  
GUSTAVO E. ROMERO ◽  
DANIELA PÉREZ ◽  
GABRIELA S. VILA
Keyword(s):  
Black Hole ◽  
Accretion Disk ◽  
Spectral Energy Distribution ◽  
Radiative Properties ◽  
Spectral Energy ◽  
Electromagnetic Spectrum ◽  
Relativistic Electrons ◽  
Black Hole Binaries ◽  
Supermassive Black Hole ◽  
Tidal Torques

An accretion disk around a supermassive black hole may be strongly perturbed by the presence of a secondary black hole. Recent simulations have shown that, under certain conditions, the tidal torques exerted by the secondary black hole may open an annular gap in the disk. In this regime, matter "overflows" across the secondary's orbit to accrete onto the primary and may feed a pair of relativistic jets. In this work we study the radiative properties of a binary system of supermassive black holes, assuming that a relativistic jet is launched from the primary and the migration of the secondary across the disk proceeds in the "overflowing" regime. The modified radiative spectrum of the disk is calculated accounting for strong gravitational effects in the innermost region. The jet emits non-thermal radiation all along the electromagnetic spectrum by interaction of locally accelerated electrons with the jet's magnetic field and internal and external radiation. In particular, we investigate whether the interaction of the relativistic electrons with the photons emitted by the accretion disk induces any signature in the spectral energy distribution of the jet that may reveal the presence of the secondary black hole.

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