Related papers: Chaos or Order in Double Barred Galaxies?
Galactic bars, made up of elongated and aligned stellar orbits, can lose angular momentum via resonant torques with dark matter particles in the halo and slow down. Here we show that if a stellar bar is decelerated to zero rotation speed,…
It is shown how the violation of the invariance of the $Z$-component of the orbital angular momentum $L_z$ in the axially symmetric potential of the Galaxy with a bar can serve as an indicator of the degree of orbital chaos of globular…
The prints of the Palomar Sky Survey, luminosity classificaiton and radial velocities were used to assign all northern Shapley-Ames galaxies to either (1) field, (2) group, or (3) cluster environments. This information for 930 galaxies…
Despite compelling evidence that stellar bars drive gas into the inner 1--2 kpc or circumnuclear (CN) region of galaxies, there are few large, high resolution studies of the CN molecular gas and star formation (SF). We study a sample of…
Self-consistent bars that form in galaxies embedded within cuspy halos are unable to flatten the cusp. Short bars form in models with quasi-flat rotation curves. They lose angular momentum to the halo through dynamical friction, but the…
Why do galactic bars rotate with high pattern speeds, when dynamical friction should rapidly couple the bar to the massive, slowly rotating dark halo? This longstanding paradox may be resolved by considering the dynamical interactions…
One of the main properties of galactic bars is their rotation (or pattern) speed, which is driven by both internal galactic properties, as well as external interactions. To assess the influence of these internal and external drivers on bar…
The phase--space volume of regions of regular or trapped motion, for bounded or scattering systems with two degrees of freedom respectively, displays universal properties. In particular, sudden reductions in the phase-space volume or gaps…
Significant fraction of barred galaxies hosts secondary bar-like structures on optical and NIR images. The circumnuclear dynamics of double-barred objects are still not well understood, observational data concerning kinematics are…
We investigate the evolution of two bars formed in fully self-consistent hydrodynamic simulations of the formation of Milky Way-mass galaxies. One galaxy shows higher central mass concentration and has a longer and stronger bar than the…
We numerically explore the behavior of repelling and aligning self-propelled polar particles (boids) in 2D enclosed by a damped flexible and elastic loop-shaped boundary. We observe disordered, polar ordered (or jammed) and circulating…
We investigate the stability of trajectories in barred galaxies with mildly triaxial halos by means of Liapunov exponents. This method is perfectly suitable for time-dependent 3D potentials where surfaces of sections and other simple…
When bars form within galaxy formation simulations in the standard cosmological context, dynamical friction with dark matter (DM) causes them to rotate rather slowly. However, almost all observed galactic bars are fast in terms of the ratio…
Although nuclear rings of gas and star formation are common in barred spiral galaxies, current theories of why and how they form do not provide the level of detail needed to quantify the effect that these rings can have on the fueling of…
The formation of two stellar bars within a galaxy has proved challenging for numerical studies. It is yet not clear whether the inner bar is born via a star formation process promoted by gas inflow along the outer bar, or whether it is…
Via mechanisms not accessible at equilibrium, self-propelled particles can form phases with positional order, such as crystals, and with orientational order, such as polar flocks. However, the interplay between these two types of order…
The extent of the continuous zone of chaotic orbits of a small-mass tertiary around a system of two gravitationally bound primaries (a double star, a double black hole, a binary asteroid, etc.) is estimated analytically, in function of the…
We have studied the evolution of the central hundred pc region of barred galaxies by performing numerical simulations realizing multi-phase nature of gas. Our simulations have shown that a stellar bar produces an oval gas ring namely the…
The presence of stars on retrograde orbits in disc galaxies is usually attributed to accretion events, both via direct accretion, as well as through the heating of the disc stars. Recent studies have shown that retrograde orbits can also be…
The halo plays a crucial role in the evolution of barred galaxies. Its near-resonant material absorbs angular momentum emitted from some of the disc particles and helps the bar become stronger. As a result, a bar (oval) forms in the inner…