Related papers: Revised research about chaotic dynamics in Manko e…
Depending on mass and rotational frequency, gravity compresses the matter in the core regions of neutron stars to densities that are several times higher than the density of ordinary atomic nuclei. At such huge densities atoms themselves…
The assumption of asymptotic flatness for isolated astrophysical bodies may be considered an approximation when one considers a cosmological context where a cosmological constant or vacuum energy is present. In this framework we study the…
As rotating neutron stars slow down, the pressure and the density in the core region increase due to the decreasing centrifugal forces and phase transitions may occur in the center. We extract the analytic behavior near the critical angular…
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…
We describe some highlights in the theory of chaos, that started with Poincare (1899). Generic systems have both ordered and chaotic domains. Chaos appears mainly near un- stable periodic orbits. Large chaotic domains are due to resonance…
We investigate turbulent gas motions in spiral galaxies and their importance to star formation in far outer disks, where the column density is typically far below the critical value for spontaneous gravitational collapse. Following the…
This work explores the dynamic properties of test particles surrounding a distorted, deformed compact object. The astrophysical motivation was to choose such background, which could constitute a more reasonable model of a real situation…
Recent numerical work by Wilson, Mathews, and Marronetti [J. R. Wilson, G. J. Mathews and P. Marronetti, Phys. Rev. D 54, 1317 (1996)] on the coalescence of massive binary neutron stars shows a striking instability as the stars come close…
The relationship between chaos and quantum mechanics has been somewhat uneasy -- even stormy, in the minds of some people. However, much of the confusion may stem from inappropriate comparisons using formal analyses. In contrast, our…
We consider a version of the Vlasov equation on the circle under a periodic potential $V(x,t)$ and a repulsing smooth interaction $W$. We suppose that the Lagrangian for the single particle has chaotic orbits; using Aubry-Mather theory and…
Neutron star glitches are commonly believed to occur, when angular momentum is transferred suddenly from the star's interior to the crust by the collective unpinning and repinning of large numbers of superfluid vortices. In general, the…
We consider the ordered and disordered dynamics for monolayers of rolling self-interacting particles with an offset center of mass and a non-isotropic inertia tensor. The rolling constraint is considered as a simplified model of a very…
In the Schwarzchild black hole spacetime, we show that chaotic motion can be triggered by the spin of a particle. Taking the spin of the particle as a perturbation and using the Melnikov method, we find that the perturbed stable and…
The dynamical stability of differentially rotating neutron stars, including hypermassive neutron stars, is of paramount importance in understanding the fate of the post-merger remnant of binary neutron stars mergers and the formation of a…
The tidal deformability and the radius of neutron stars are observables, which have been used to constrain the neutron star equation of state and explore the composition in neutron stars. We investigated the radius and tidal deformability…
This book chapter explores key aspects of neutron stars, pulsar glitches, tidal deformability, fast pulsars, the equation of state, and strange quark matter stars. Challenges in directly measuring neutron star radius have led to reliance on…
We present new results on dynamical instabilities in rapidly rotating neutron-stars. In particular, using numerical simulations in full General Relativity, we analyse the effects that the stellar compactness has on the threshold for the…
Positions of a charged particle's equilibrium orbits and spatial regions where the chaos bound is violated are found through circular motions of the particle around charged Taub-NUT black holes. Lyapunov exponent is gotten by calculating…
We investigate induced oscillations by the gravitational field of a fast stellar object, such as a neutron star or a black-hole in a near miss collision with another star. Non-adiabatic collision conditions may lead to large amplitude…
The unknown state of matter at ultra-high density, large proton/neutron number asymmetry, and low temperature is a major long-standing problem in modern physics. Neutron stars provide the only known setting in the Universe where matter in…