Accretion disk dynamics

Kubsch, Marcus; Illenseer, Tobias F.; Duschl, W. J.

doi:10.1051/0004-6361/201527092

Cited by 2 publications

(1 citation statement)

References 29 publications

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“…Whether self-gravitating disks fragment, and the determination of the number and dimensions of the disk debris, depend on several parameters-tori masses with respect to attractor, and the rate of energy loss and cooling. Fragmentation, on the other hand, can provide a context in the galactic environment for stars and regular spiral structure waves formation (Abbassi et al 2013, Alexander et al 2008, Anthony & Carlberg 1988, Bertin & Lodato 1999, 2001, Ghasemnezhad & Abbassi 2016, Hunter 1963, Kubsch et al 2016, Lodato 2007, Shadmehri & Khajenab 2006, Shlosman & Begelman 1987, 1989, Tohline & Hachisu 1990, Woodward et al 1994. Also, rotation of disks in the central part of various galaxies, for example NGC4258, shows a divergence from the Keplerian rotation law- (Herrnstein et al 1998a,b).…”

Section: Tori Self-gravity and Rad Instabilitiesmentioning

confidence: 99%

Relating Kerr SMBHs in active galactic nuclei to RADs configurations

Pugliese

Stuchlík

2018

Class. Quantum Grav.

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There is strong observational evidence that many active galactic nuclei (AGNs) harbour supermassive black holes (SMBHs), demonstrating multi-accretion episodes during their life-time. In such AGNs, corotating and counterrotating tori, or strongly misaligned disks, as related to the central Kerr SMBH spin, can report traces of the AGNs evolution. Here we concentrate on aggregates of accretion disks structures, ringed accretion disks (RADs) orbiting a central Kerr SMBH, assuming that each torus of the RADs is centered in the equatorial plane of the attractor, tori are coplanar and axi-symmetric. Many of the RAD aspects are governed mostly by the spin of the Kerr geometry. We classify Kerr black holes (BHs) due to their dimensionless spin, according to possible combinations of corotating and counterrotating equilibrium or unstable (accreting) tori composing the RADs. The number of accreting tori in RADs cannot exceed n = 2. We present list of 14 characteristic values of the Kerr BH dimensionless spin a governing the classification in whole the black hole range 0 ≤ a ≤ M , uniquely constrained by the RAD properties. The spin values are remarkably close providing an accurate characterization of the Kerr attractors based on the RAD properties. RAD dynamics is richer in the spacetimes of high spin values. One of the critical predictions states that a RAD tori couple formed by an outer accreting corotating and an inner accreting counterrotating torus is expected to be observed only around slowly spinning (a < 0.46M ) BHs. The analysis strongly binds the fluid and BH characteristics providing indications on the situations where to search for RADs observational evidences. Obscuring and screening tori, possibly evident as traces in X-ray spectrum emission, are strongly constrained, eventually ruling out many assumptions used in the current investigations of the screening effects.We expect relevance of our classification of Kerr spacetimes in relation to astrophysical phenomena arising in different stages of AGNs life that could be observed by the planned X-ray satellite observatory ATHENA (Advanced Telescope for High ENergy Astrophysics).

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Section: Tori Self-gravity and Rad Instabilitiesmentioning

confidence: 99%

Relating Kerr SMBHs in active galactic nuclei to RADs configurations

Pugliese

Stuchlík

2018

Class. Quantum Grav.

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Structure of the self-gravitating accretion discs in the presence of outflow

Ghanbarnejad

Ghasemnezhad

2020

Monthly Notices of the Royal Astronomical Society

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Numerical simulations of self-gravitating accretion discs have shown that the evolution of such systems depends strongly on the rate at which it cools. In this work, we study the vertical structure of the self-gravitating accretion discs and also investigate the effect of the cooling rate on the latitudinal structure of such accretion discs. In the spherical coordinates, we write the hydrodynamics equations and simplify the basic equations based on the assumptions of axisymmetric and steady state. We use the self-similar method for solving the equations in the radial direction and we find proper boundary conditions. We find inflow–outflow solutions by considering the meridional component of the velocity field. In order to formulate the cooling term in energy equation, we introduce the new parameter β as a free constant that is the cooling time-scale in units of the dynamical time-scale. Our numerical solutions show that the thickness of the disc decreases with smaller β (or increasing the cooling term in energy equation) and it makes the disc colder and outflows form in the regions with lower latitude. So by increasing the cooling rate in the disc, the regions which belong to inflow decrease.

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Accretion disk dynamics

Cited by 2 publications

References 29 publications

Relating Kerr SMBHs in active galactic nuclei to RADs configurations

Relating Kerr SMBHs in active galactic nuclei to RADs configurations

Structure of the self-gravitating accretion discs in the presence of outflow

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