Self-Similar Perturbation of an Accretion Disc around Merging Black Holes

Жилкин, А. Г.; Bisikalo, D. V.

doi:10.1134/s1063772921110081

Cited by 4 publications

(6 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Note that Eq. ( 17) is a non-axisymmetric generalization of a formula written down in Zhilkin & Bisikalo (2021) (see their equation 20). Those authors also consider the dynamical equation for the vertical velocity (their equation 17), but with a prescribed Gaussian vertical pressure profile (and thus no fluid-vacuum interface) and no turbulent viscosity terms.…”

Section: Preliminaries and Final Equationsmentioning

confidence: 99%

“…Also note that axisymmetric versions of some of our results (e.g. the disk height evolution equation) appear in Zhilkin & Bisikalo (2021); they consider a dynamical equation for the vertical velocity, but with a prescribed Gaussian vertical pressure profile and no turbulent viscosity terms. Nontrivial vertical dynamics were also considered in specialized coordinates to study eccentric disk evolution in Ogilvie (2001).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Dynamical Thin Disks

Westernacher-Schneider¹

2023

Preprint

View full text Add to dashboard Cite

Thin disk accretion is often modeled in highly dynamical settings using the two-dimensional equations of viscous hydrodynamics, with viscosity representing unresolved turbulence. These equations are supposed to arise after vertical integration of the full three-dimensional equations of hydrodynamics, under the assumption of a geometrically thin disk with mirror symmetry about the midplane. However, in the dynamical context, vertical dynamics are neglected by incorrectly assuming instantaneous vertical hydrostatic equilibrium. The resulting errors in the local disk height couple to the horizontal dynamics through the α-viscosity prescription and disk height-dependent gravitational softening models. Furthermore, the viscous terms in the horizontal equations are only complete if they are inserted after vertical integration, as if the system is actually two-dimensional. Since turbulence breaks mirror symmetry, it is more physically correct to insert a turbulence model at the three-dimensional level, and impose mirror symmetry only on average. Thus, some viscous terms are usually missing. With these considerations in mind, we revisit the vertical integration procedure, restricting to the regime of a Newtonian, non-self-gravitating disk. We obtain six evolution equations with only horizontal dependence, which determine the local vertical position and velocity of the disk surface, in addition to the usual surface densities of mass, horizontal momentum, and energy. This "2.5-dimensional" formulation opens the door to efficiently study vertical oscillations of thin disks in dynamical settings, and to improve the treatment of unresolved turbulence. As a demonstration, by including viscous stress at the three-dimensional level, we recover missing viscous terms which involve the vertical variables. We also propose a resummation of the vertically integrated gravitational force, which has a strikingly similar radial profile to a gravitational softening model advocated for in protoplanetary disk studies.

show abstract

Section: Preliminaries and Final Equationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Dynamical Thin Disks

Westernacher-Schneider¹

2023

Preprint

View full text Add to dashboard Cite

show abstract

“…Note that Eq. ( 17) is a nonaxisymmetric generalization of a formula written down in [17] [see their Eq. ( 20)].…”

Section: Vertical Dynamicsmentioning

confidence: 99%

“…Also note that axisymmetric versions of some of our results (e.g. the disk height evolution equation) appear in [17]; they consider a dynamical equation for the vertical velocity, but with a prescribed Gaussian vertical pressure profile and no turbulent viscosity terms. Nontrivial vertical dynamics were also considered in specialized coordinates to study eccentric disk evolution in [5].…”

Section: Introductionmentioning

confidence: 99%

Dynamical thin disks

Westernacher-Schneider

2023

Phys. Rev. D

View full text Add to dashboard Cite

Thin disk accretion is often modeled in highly dynamical settings using the two-dimensional equations of viscous hydrodynamics, with viscosity representing unresolved turbulence. These equations are supposed to arise after vertical integration of the full three-dimensional equations of hydrodynamics, under the assumption of a geometrically thin disk with mirror symmetry about the midplane. However, in the dynamical context, vertical dynamics are neglected by incorrectly assuming instantaneous vertical hydrostatic equilibrium. The resulting errors in the local disk height couple to the horizontal dynamics through the α-viscosity prescription and disk height-dependent gravitational softening models. Furthermore, the viscous terms in the horizontal equations are only complete if they are inserted after vertical integration, as if the system is actually two-dimensional. Since turbulence breaks mirror symmetry, it is more physically correct to insert a turbulence model at the three-dimensional level and impose mirror symmetry only on average. Thus, some viscous terms are usually missing. With these considerations in mind, we revisit the vertical integration procedure, restricting ourselves to the regime of a Newtonian, nonself-gravitating disk. We obtain six evolution equations with only horizontal dependence, which determine the local vertical position and velocity of the disk surface, in addition to the usual surface densities of mass, horizontal momentum, and energy. This "2.5-dimensional" formulation opens the door to efficiently study vertical oscillations of thin disks in dynamical settings, and to improve the treatment of unresolved turbulence. As a demonstration, by including viscous stress at the three-dimensional level, we recover missing viscous terms which involve the vertical variables. We also propose a resummation of the vertically integrated gravitational force, which has a strikingly similar radial profile to a gravitational softening model advocated for in protoplanetary disk studies.

show abstract

“…The generation of shock waves leads to the heating of matter within the accretion disk, resulting in the production of electromagnetic radiation. As a result, the perturbation induces shock waves, which, in turn, impact various aspects of the system, such as the light curve, radiation spectrum (including QP Os), and outburst durations (Zhilkin & Bisikalo 2021). The physical origins of QPO frequencies are not yet fully understood (Ingram & Motta 2019).…”

Section: Introductionmentioning

confidence: 99%

Study of Asymptotic Velocity in the Bondi–Hoyle Accretion Flows in the Domain of Kerr and 4-D Einstein–Gauss–Bonnet Gravities

2022

View full text Add to dashboard Cite

Understanding the physical structures of the accreted matter very close to a black hole in quasars and active galactic nucleus (AGN) is an important milestone to constrain the activities occurring in their centers. In this paper, we numerically investigate the effects of the asymptotic velocities on the physical structures of the accretion disk around the Kerr and Einstein–Gauss–Bonnet (EGB) rapidly rotating black holes. The Bondi–Hoyle accretion is considered with a falling gas towards the black hole in an upstream region of the computational domain. Shock cones are naturally formed in the downstream part of the flow around both black holes. The structure of the cones and the amount of the accreted matter depend on asymptotic velocity V∞ (Mach number) and the types of the gravities (Kerr or EGB). Increasing the Mach number of the in-flowing matter in the supersonic region reduces the shock opening angle and the accretion rates, because of the gas rapidly falling towards the black hole. The EGB gravity leads to an increase in the shock opening angle of the shock cones while the mass-accretion rates dM/dt decrease in EGB gravity with a Gauss–Bonnet (GB) coupling constant α. It is also confirmed that accretion rates and drag forces are significantly altered in the EGB gravity. Our numerical simulation results could be used in identifying the accretion mechanism and physical properties of the accretion disk and black hole in the observed X-rays such as NGC 1313 X-1 and 1313 X-2 and MAXI J1803-298.

show abstract

Self-Similar Perturbation of an Accretion Disc around Merging Black Holes

Cited by 4 publications

References 35 publications

Dynamical Thin Disks

Dynamical Thin Disks

Dynamical thin disks

Study of Asymptotic Velocity in the Bondi–Hoyle Accretion Flows in the Domain of Kerr and 4-D Einstein–Gauss–Bonnet Gravities

Contact Info

Product

Resources

About