Related papers: Accretion Disks Phase Transitions: 2-D or not 2-D?
We describe astrophysical processes around a black hole keeping primarily the physics of accretion in mind. In Section 1, we briefly discuss the formation, evolution and detection of black holes. We also discuss the difference of flow…
A major uncertainty in accretion disk theory is the nature and properties of gas turbulence, which drives transport in protoplanetary disks. The commonly used viscous prescription for the Maxwell-Reynolds stress tensor gives rise to a…
Regions of stellar and planetary interiors that are unstable according to the Schwarzschild criterion, but stable according to the Ledoux criterion, are subject to a form of oscillatory double-diffusive (ODD) convection often called…
Several physical and astrophysical problems related to accretion onto black holes and neutron stars are shortly reviewed. I discuss the observed differences between these two types of compact objects in quiescent Soft X-ray Transients. Then…
Using three-dimensional general relativistic magnetohydrodynamic simulations with electron and proton thermodynamics and an electron cooling function, we probe the inner radial and vertical structure of weakly magnetized geometrically thin…
In this paper, we extend our previous analysis (Lodato & Rice 2004) of the transport properties induced by gravitational instabilities in cooling, gaseous accretion discs to the case where the disc mass is comparable to the central object.…
When an accretion disk surrounds a binary rotating in the same sense, the binary exerts strong torques on the gas. Analytic work in the 1D approximation indicated that these torques sharply diminish or even eliminate accretion from the disk…
We study the local thermal stability of thin accretion disks. We present a full stability analysis in the presence of a magnetic field and more importantly wind. For wind, we use a general model suitable for adequately describing several…
Context. The origin of giant planets at moderate separations $\simeq$$1$$-$$10$ au is still not fully understood because numerical studies of Type II migration in protoplanetary disks often predict a decay of the semi-major axis that is too…
Under the influence of oscillatory shear, a mono-layer of frictional granular disks exhibits two dynamical phase transitions: a transition from an initially disordered state to an ordered crystalline state, and a dynamic active-absorbing…
Our understanding of the dynamical processes which control the structure and evolution of the interaction region between an accretion disk and the central star is reviewed. If the central star is unmagnetized, this interaction is in the…
A protostellar disk is threaded by a static magnetic field that is perpendicular to the disk-surface. The magnetic field acts to brake the protostellar disk and cause the disk material to move towards the protostar. General analytic…
In order to study the outflows from accretion disks, we solve the set of hydrodynamic equations for accretion disks in the spherical coordinates ($r\theta\phi$) to obtain the explicit structure along the $\theta$ direction. Using…
We introduce the problem of partitioning 2D regions (usually convex regions) into mutually congruent pieces ('tiles').
Most analytic work to date on protostellar disks has focused on those in isolation from their environments. However, observations are now beginning to probe the earliest, most embedded phases of star formation, during which disks are…
In this paper we study a system of advection-diffusion equations in a bulk domain coupled to an advection-diffusion equation on an embedded surface. Such systems of coupled partial differential equations arise in, for example, the modeling…
We review our current knowledge of thermal and viscous instabilities in accretion discs around compact objects. We begin with classical disc models based on analytic viscosity prescriptions, discussing physical uncertainties and exploring…
In this chapter, we review some of the interesting consequences that tilt between the spin axis of the black hole and angular momentum axis of the accretion disk can have on the dynamics, thermodynamics, and observational appearance of…
In this thesis, I study hydrodynamical models of slim accretion disks --- advective, optically thick disks which generalize the standard models of radiatively efficient thin disks to all accretion rates. I start with a general introduction…
The responses of perturbations added into the optically thick, advection-dominated accretion disk (ADAD), what we call the slim disk (SD), are investigated through numerical simulations. Although it is proposed that the SD is thermally…