# ANGULAR MOMENTUM TRANSPORT BY ACOUSTIC MODES GENERATED IN THE BOUNDARY LAYER. I. HYDRODYNAMICAL THEORY AND SIMULATIONS

## Abstract

The nature of angular momentum transport in the boundary layers of accretion disks has been one of the central and long-standing issues of accretion disk theory. In this work we demonstrate that acoustic waves excited by supersonic shear in the boundary layer serve as an efficient mechanism of mass, momentum, and energy transport at the interface between the disk and the accreting object. We develop the theory of angular momentum transport by acoustic modes in the boundary layer, and support our findings with three-dimensional hydrodynamical simulations, using an isothermal equation of state. Our first major result is the identification of three types of global modes in the boundary layer. We derive dispersion relations for each of these modes that accurately capture the pattern speeds observed in simulations to within a few percent. Second, we show that angular momentum transport in the boundary layer is intrinsically nonlocal, and is driven by radiation of angular momentum away from the boundary layer into both the star and the disk. The picture of angular momentum transport in the boundary layer by waves that can travel large distances before dissipating and redistributing angular momentum and energy to the disk and star is incompatible with themore »

- Authors:

- Publication Date:

- OSTI Identifier:
- 22127121

- Resource Type:
- Journal Article

- Journal Name:
- Astrophysical Journal

- Additional Journal Information:
- Journal Volume: 770; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCRETION DISKS; ANGULAR MOMENTUM; BOUNDARY LAYERS; DISPERSION RELATIONS; EQUATIONS OF STATE; HYDRODYNAMICS; INSTABILITY; SIMULATION; SOUND WAVES; STARS; THREE-DIMENSIONAL CALCULATIONS; TRANSPORT THEORY; TURBULENCE; VELOCITY

### Citation Formats

```
Belyaev, Mikhail A., Rafikov, Roman R., and Stone, James M., E-mail: rrr@astro.princeton.edu.
```*ANGULAR MOMENTUM TRANSPORT BY ACOUSTIC MODES GENERATED IN THE BOUNDARY LAYER. I. HYDRODYNAMICAL THEORY AND SIMULATIONS*. United States: N. p., 2013.
Web. doi:10.1088/0004-637X/770/1/67.

```
Belyaev, Mikhail A., Rafikov, Roman R., & Stone, James M., E-mail: rrr@astro.princeton.edu.
```*ANGULAR MOMENTUM TRANSPORT BY ACOUSTIC MODES GENERATED IN THE BOUNDARY LAYER. I. HYDRODYNAMICAL THEORY AND SIMULATIONS*. United States. doi:10.1088/0004-637X/770/1/67.

```
Belyaev, Mikhail A., Rafikov, Roman R., and Stone, James M., E-mail: rrr@astro.princeton.edu. Mon .
"ANGULAR MOMENTUM TRANSPORT BY ACOUSTIC MODES GENERATED IN THE BOUNDARY LAYER. I. HYDRODYNAMICAL THEORY AND SIMULATIONS". United States. doi:10.1088/0004-637X/770/1/67.
```

```
@article{osti_22127121,
```

title = {ANGULAR MOMENTUM TRANSPORT BY ACOUSTIC MODES GENERATED IN THE BOUNDARY LAYER. I. HYDRODYNAMICAL THEORY AND SIMULATIONS},

author = {Belyaev, Mikhail A. and Rafikov, Roman R. and Stone, James M., E-mail: rrr@astro.princeton.edu},

abstractNote = {The nature of angular momentum transport in the boundary layers of accretion disks has been one of the central and long-standing issues of accretion disk theory. In this work we demonstrate that acoustic waves excited by supersonic shear in the boundary layer serve as an efficient mechanism of mass, momentum, and energy transport at the interface between the disk and the accreting object. We develop the theory of angular momentum transport by acoustic modes in the boundary layer, and support our findings with three-dimensional hydrodynamical simulations, using an isothermal equation of state. Our first major result is the identification of three types of global modes in the boundary layer. We derive dispersion relations for each of these modes that accurately capture the pattern speeds observed in simulations to within a few percent. Second, we show that angular momentum transport in the boundary layer is intrinsically nonlocal, and is driven by radiation of angular momentum away from the boundary layer into both the star and the disk. The picture of angular momentum transport in the boundary layer by waves that can travel large distances before dissipating and redistributing angular momentum and energy to the disk and star is incompatible with the conventional notion of local transport by turbulent stresses. Our results have important implications for semianalytical models that describe the spectral emission from boundary layers.},

doi = {10.1088/0004-637X/770/1/67},

journal = {Astrophysical Journal},

issn = {0004-637X},

number = 1,

volume = 770,

place = {United States},

year = {2013},

month = {6}

}