Related papers: An Instability in Triaxial Stellar Systems
A new element is proposed to play a role in the evolution of extrasolar planetary systems: the tidal (or elliptical) instability. It comes from a parametric resonance and takes place in any rotating fluid whose streamlines are (even…
The evolution in shape of an isolated density enhancement in the early universe is studied through numerical simulations. The formation scenarios of a cold dissipationless collapse and that of a slow accumulation of gas in a dark matter…
Assuming the dark matter halo of the Milky Way as a non-spherical potential (i.e. triaxial, prolate, oblate), we show how the assembling process of the Milky Way halo, may have left long lasting stellar halo kinematic fossils only due to…
This paper investigates spheroidal galaxies comprising a self-interacting dark matter halo (SIDM) plus de Vaucouleurs stellar distribution. These are coupled only via their shared gravitational field, which is computed consistently from the…
N-body simulations of disc galaxies that display recurrent transient spiral patterns are comparatively easy to construct, but are harder to understand. In this paper, I summarise the evidence from such experiments that the spiral patterns…
A substantial fraction of the warps in spiral galaxies may result from bending instabilities if the disks are essentially self-gravitating. With N-body simulations, we show that galaxies with self-gravitating disks as thick as HI disks are…
We study spherical and disk clusters in a near-Keplerian potential of galactic centers or massive black holes. In such a potential orbit precession is commonly retrograde, i.e. direction of the orbit precession is opposite to the orbital…
We present $N$--body models for triaxial elliptical galaxies or halos of galaxies, which are fully self--gravitating, have near constant axis ratio as a function of radius and a $r^{-1}$ central density cusp. Preliminary investigation…
Perturbations of rotating relativistic stars can be classified by their behavior under parity. For axial perturbations (r-modes), initial data with negative canonical energy is found with angular dependence $e^{im\phi}$ for all values of…
Based on N-body simulations, we show that realistic galactic disks are subject to bending instabilities of fire-hose type when the disks are substantially self-gravitating, that is, if they contain dark matter distributed in the disk.…
The dissipative infall of gas during the formation of a galaxy modifies the density profile and shape of the dark halo. Gas dissipates energy radiatively and sinks to the center of the dark halo forming the luminous part of a galaxy. The…
The dark matter halos in $\Lambda$CDM cosmological simulations are triaxial and highly flattened. In many cases, these triaxial equilibria are also tumbling slowly, typically about their short axes, with periods of order a Hubble time.…
Orbital motion in triaxial nuclei with central point masses, representing supermassive black holes, is investigated. The stellar density is assumed to follow a power law, rho ~ 1/r^gamma, with gamma=1 or gamma=2. At low energies the motion…
Recent studies have presented evidence that the Milky Way global potential may be nonspherical. In this case, the assembling process of the Galaxy may have left long lasting stellar halo kinematic fossils due to the shape of the dark matter…
The well-known bar instability of rotationally-supported disk galaxy models has been studied extensively since its first discovery over half a century ago. We were therefore very surprised to find cases of disks embedded in rigid halos,…
We study the regular or chaotic character of orbits in a 3D dynamical model, describing a triaxial galaxy surrounded by a spherical dark halo component. Our numerical experiments suggest that the percentage of chaotic orbits decreases…
We examine the bar instability in galactic models with an exponential disk and a cuspy dark matter (DM) halo with a Navarro-Frenk-White (NFW) cosmological density profile. We construct equilibrium models from a 3-integral composite…
In order to address the question of whether spiral disturbances in galaxy discs are gravitationally coupled to the halo, we conduct simulations of idealized models of disc galaxies. We compare growth rates of spiral instabilities in…
The results of numerical simulations of the dynamics of galactic disks, which are submerged into nonaxisymmetric dark massive halo are discussed. Galaxy disks dynamics in the nonaxisymmetric (triaxial) dark halo were investigated in detail…
Cuspy triaxial potentials admit a large number of chaotic orbits, which moreover exhibit extreme "stickiness" that makes the process of chaotic mixing surprisingly inefficient. Environmental effects, modeled as noise and/or periodic…