Related papers: Dynamical Bar Instability in Relativistic Rotating…
We present the first calculations of the gravitational radiation produced by nonaxisymmetric dynamical instability in a rapidly rotating compact star. The star deforms into a bar shape, shedding $\sim 4\%$ of its mass and $\sim 17\%$ of its…
We perform fully general relativistic simulations of rotating stellar core collapse in three spatial dimension. A parametric equation of state is adopted following Dimmelmeier et al. The early stage of the collapse is followed by an…
A one-armed spiral instability has been found to develop in differentially rotating stellar models that have a relatively stiff, $n=1$ polytropic equation of state and a wide range of rotational energies. This suggests that such…
We show that magnetic fields stronger than about $10^{15}$ G are able to suppress the development of the hydrodynamical bar-mode instability in relativistic stars. The suppression is due to a change in the rest-mass density and angular…
This paper considers gravitational perturbations in geometrically thin disks with rotation curves dominated by a central object, but with substantial contributions from magnetic pressure and tension. The treatment is general, but the…
We find that nuclear rings in barred galaxies can be subject to a new type of non-self-gravitational dynamical instability. The instability leads to the formation of gaseous molecular bars with pattern speeds which are substantially slower…
We present the first attempt to analyse the growth of the bar instability in stellar-gaseous disks evolving in a fully consistent cosmological scenario. We explored the role of the cosmology on pure stellar disks with different mass…
R-modes of neutron stars could be a source of gravitational waves for ground based detectors. If the precise frequency $\sigma$ is known, guided gravitational wave searches with enhanced detectability are possible. Because of its physical…
We investigate the dynamical one-armed spiral instability in differentially rotating stars with both eigenmode analysis and hydrodynamic simulations in Newtonian gravity. We find that the one-armed spiral mode is generated around the…
Recent observational constraints restrict the strict applicability of stellar dynamics in spirals to a few rotation periods. However, stellar dynamics concepts such as periodic orbits are invaluable for understanding the various dynamical…
We investigate the nonlinear behaviour of the dynamically unstable rotating star for the bar mode by three-dimensional hydrodynamics in Newtonian gravity. We find that an oscillation along the rotation axis is induced throughout the growth…
Luminous blue variables are an intermediate stage in the evolution of high-mass stars characterized by extreme mass loss and substantial variability. The stars show large irregular episodic variations on timescales of years to decades in…
Many strong simulated galactic bars experience buckling instability, which manifests itself as a vertical distortion out of the disk plane, and later dissipates. Using a simulation of an isolated Milky Way-like galaxy, I demonstrate that…
N-body simulations have shown that a bar in a galaxy can be triggered by two processes: (1) by its own instabilities in the disk, or (2) by interactions with other galaxies. Both mechanisms have been widely studied. However, the literature…
We study gravitational instability and consequent star formation in a wide range of isolated disk galaxies, using three-dimensional, smoothed particle hydrodynamics simulations at resolution sufficient to fully resolve gravitational…
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…
Several recent surprises appear dramatically to have improved the likelihood that the spin of rapidly rotating, newly formed neutron stars (and, possibly, of old stars spun up by accretion) is limited by a nonaxisymmetric instability driven…
We investigate the nature of low T/W dynamical instabilities in various ranges of the stiffness of the equation of state in differentially rotating stars. Here T is the rotational kinetic energy, while W the gravitational binding energy. We…
We construct constant rest-mass sequences of equilibrium models of differentially rotating neutron stars which resemble binary neutron star post-merger remnants. For a more realistic description of the post-merger remnant, we impose that…
We perform simulations of relativistic binary stars in post-Newtonian gravity to investigate their dynamical stability prior to merger against gravitational collapse in a tidal field. In general, our equations are only strictly accurate to…