Related papers: The Stability of Disks in Cusped Potentials
I review the arguments for the importance of halo structure in driving galaxy evolution and coupling a galaxy to its environment. We begin with a general discussion of the key dynamics and examples of structure dominated by modes. We find…
An earlier paper presented the potentially significant discovery that disturbances in simplified simulations of a stellar disc model that was predicted to be stable in linear theory grew to large amplitude over a long period of time. The…
In this paper, we show that astrophysical accretion disks are dynamically unstable to non-axisymmetric disturbances. This instability is present in any stably stratified anticyclonically sheared flow as soon as the angular velocity…
We study the linear $m=1$ counter-rotating instability in a two-component, nearly Keplerian disc. Our goal is to understand these \emph{slow} modes in discs orbiting massive black holes in galactic nuclei. They are of interest not only…
We investigate the Jeans instability of a galactic disk embedded in a dynamically responsive dark halo. It is shown that the disk-halo system becomes nominally Jeans unstable. On small scales the instability is suppressed, if the Toomre…
Disks of low-mass bodies scattered by giant planets to large semi-major axis and constant periapsis orbits are vulnerable to a buckling instability. This instability exponentially grows orbital inclinations, raises periapsis distances, and…
We investigate the convective stability of two popular types of model of the gas distribution in the hot Galactic halo. We first consider models in which the halo density and temperature decrease exponentially with height above the disk.…
Galactic bars are unstable to a vertical buckling instability which heats the disk and in some cases forms a boxy/peanut shaped bulge. We analyze the buckling instability as an application of classical Euler buckling followed by nonlinear…
The stability properties of inviscid protostellar disks are examined taking into account the Hall effect and buoyancy. Depending on the parameters, different types of instabilities can exist in different regions of disks. In a very low…
We analyse the buckling stability of a thin, viscous sheet when subject to simple shear, providing conditions for the onset of the dominant out-of-plane modes using two models: (i) an asymptotic theory for the dynamics of a viscous plate…
Vertical shear instability (VSI), driven by a vertical gradient of rotational angular velocity, is a promising source of turbulence in protoplanetary disks. We examine the semi-global stability of thermally stratified disks and find that…
We present a numerical study of a two dimensional granular medium consisting of hard inelastic disks. The evolution of the medium throughout a cooling process is monitored. Two different types of instabilities (shearing and clustering…
We investigate the effects of ambipolar diffusion and the Hall effect on the stability of weakly-ionized, magnetized planar shear flows. Employing a local approach similar to the shearing-sheet approximation, we solve for the evolution of…
The absence of thermal instability in the high/soft state of black hole X-ray binaries, in disagreement with the standard thin disk theory, is a long-standing riddle for theoretical astronomers. We have tried to resolve this question by…
It is well-established that strong bars rotating in dense halos generally slow down as they lose angular momentum to the halo through dynamical friction. Angular momentum exchanges between the bar and halo particles take place at…
We study the growth of galactic disks in live triaxial DM halos. The halos have been assembled through constrained realizations method and evolved from the linear regime using cosmological simulations. The `seed' disks have been inserted at…
We revisit the diffusive instability in dusty disks that arises when the dust mass diffusivity and/or viscosity decreases sufficiently steeply with increasing dust density. Our updated model includes an incompressible, viscous gas that…
The standard thin disk model predicts that when the accretion rate is over a small fraction of the Eddington rate, which corresponds to $L \ga 0.06 L_{Edd}$, the inner region of the disk is radiation-pressure-dominated and thermally…
We employ an improved methodology to insert live stellar disks into high-resolution dark matter simulations of Milky Way sized halos, allowing us to investigate the fate of thin stellar disks in the tumultuous environment of cold dark…
We investigate the dynamical instability of the one-armed spiral m=1 mode in differentially rotating stars by means of 3+1 hydrodynamical simulations in Newtonian gravitation. We find that both a soft equation of state and a high degree of…