Counter-rotating accretion discs

Dyda, Sergei; Lovelace, R. V. E.; Ustyugova, G. V.; Romanova, M. M.; Koldoba, A. V.

doi:10.1093/mnras/stu2131

Cited by 33 publications

(30 citation statements)

References 26 publications

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“…Disc shrinkage due to counter rotanew feature from the "inner disc", but the outer ring could sometimes be referred to as an "outer tilted disc", as the "ring" spirals in into the inner disc and the borders between the zones are not always well defined. tion has been demonstrated in idealized simulations of protostellar discs (Dyda et al 2015).…”

Section: Discussionmentioning

confidence: 94%

Four phases of angular-momentum buildup in high-z galaxies: from cosmic-web streams through an extended ring to disc and bulge

Danovich¹,

Dekel²,

Hahn³

et al. 2015

Monthly Notices of the Royal Astronomical Society

308

377

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We study the angular-momentum (AM) buildup in high-z massive galaxies using highresolution cosmological simulations. The AM originates in co-planar streams of cold gas and merging galaxies tracing cosmic-web filaments, and it undergoes four phases of evolution. (I) Outside the halo virial radius (R v ∼ 100 kpc), the elongated streams gain AM by tidal torques with a specific AM (sAM) ∼ 1.7 times the dark-matter (DM) spin due to the gas' higher quadrupole moment. This AM is expressed as stream impact parameters, from ∼ 0.3R v to counter rotation. (II) In the outer halo, while the incoming DM mixes with the existing halo of lower sAM to a spin λ dm ∼ 0.04, the cold streams transport the AM to the inner halo such that their spin in the halo is ∼ 3λ dm . (III) Near pericenter, the streams dissipate into an irregular rotating ring extending to ∼ 0.3R v and tilted relative to the inner disc. Torques exerted partly by the disc make the ring gas lose AM, spiral in, and settle into the disc within one orbit. The ring is observable with 30% probability as a damped Lyman-α absorber. (IV) Within the disc, < 0.1R v , torques associated with violent disc instability drive AM out and baryons into a central bulge, while outflows remove low-spin gas, introducing certain sensitivity to feedback strength. Despite the different AM histories of gas and DM, the disc spin is comparable to the DM-halo spin. Counter rotation can strongly affect disc evolution.

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Section: Discussionmentioning

confidence: 94%

Four phases of angular-momentum buildup in high-z galaxies: from cosmic-web streams through an extended ring to disc and bulge

Danovich¹,

Dekel²,

Hahn³

et al. 2015

Monthly Notices of the Royal Astronomical Society

308

377

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“…As a sideline result to the RAD investigation a comparative analysis of the corotating and counterrotating tori is obtained in dependence of the central Kerr black hole spinto-mass ratio. The hypothesis that counterrotating tori can be formed around supermassive Kerr BHs has already been addressed in literature, for example in [45,46,47,90]. However, we have been carried out here a focused investigation, providing a detailed comparative analysis of the two classes of accreting tori.…”

Section: Tori Edges and Elongationmentioning

confidence: 99%

RADs energetics and constraints on emerging tori collisions around super-massive Kerr black holes

Pugliese

Stuchlík

2019

Eur. Phys. J. C

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We provide constraints on possible configurations and interactions of two coplanar tori orbiting a central Kerr black hole (BH), in dependence on its dimensionless spin. The two-tori configurations can be directly linked to the current models featuring the obscuration of galactic BH X-ray emission. The emergence of each torus instability phases is discussed and tori collision has been also investigated. The first simple evaluation of the center-of-mass energy proves that collision-energy-efficiency increases with the dimensionless BH spin. We explore the phenomenological aspects of the corotating and counterrotating tori by analyzing properties of the orbiting toroidal configurations related to the fluid enthalpy flux, the mass-flux, the mass-accretion-rates, and the cusp luminosity in the two cases of corotating and counterrotating fluids in dependence on the SMBH spin. The analysis resulted ultimately in a comparative investigation of the properties of corotating versus counterrotating tori, demonstrating that two accretion tori can orbit around the central Kerr attractor only under very specific conditions. Our results also demonstrate that the dynamics of the unstable phases of these double tori systems is significant for the high energy phenomena which could be observable in the X-ray emission and extremely energetic phenomena in active galactic nuclei and quasar.

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“…In an early study by Kuznetsov et al (1999) the effective viscosity was the numerical viscosity due to the finite grid. In a recent study by Dyda et al (2014), a high resolution grid was used with all components of the viscous stress tensor are included to model an isotropic Shakura-Sunyaev α−viscosity.…”

Section: Discussionmentioning

confidence: 99%

“…There is limited evidence of counterrotating gas components in discs around stars (Remijan and Hollis 2006;Tang et al 2012). Theory and simulations of co/counter-rotating gas/gas discs around stars and black holes predict enormously enhanced accretion rates resulting from the presence of the two components which can give rise to outbursts from these discs (Lovelace and Chou 1996;Kuznetsov et al 1999;Nixon, King, and Price 2012;Dyda et al 2014). …”

Section: Introductionmentioning

confidence: 99%

Kelvin–Helmholtz instability of counter-rotating discs

Quach

Dyda

Lovelace

2014

Monthly Notices of the Royal Astronomical Society

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Observations of galaxies and models of accreting systems point to the occurrence of counter-rotating discs where the inner part of the disc (r < r 0 ) is co-rotating and the outer part is counter-rotating. This work analyzes the linear stability of radially separated co-and counter-rotating thin discs. The strong instability found is the supersonic Kelvin-Helmholtz instability. The growth rates are of the order of or larger than the angular rotation rate at the interface. The instability is absent if there is no vertical dependence of the perturbation. That is, the instability is essentially threedimensional. The nonlinear evolution of the instability is predicted to lead to a mixing of the two components, strong heating of the mixed gas, and vertical expansion of the gas, and annihilation of the angular momenta of the two components. As a result the heated gas will free-fall towards the disc's center over the surface of the inner disc.

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Counter-rotating accretion discs

Cited by 33 publications

References 26 publications

Four phases of angular-momentum buildup in high-z galaxies: from cosmic-web streams through an extended ring to disc and bulge

Four phases of angular-momentum buildup in high-z galaxies: from cosmic-web streams through an extended ring to disc and bulge

RADs energetics and constraints on emerging tori collisions around super-massive Kerr black holes

Kelvin–Helmholtz instability of counter-rotating discs

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