Related papers: Bars and the connection between dark and visible m…
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…
Although nearly one-third of barred galaxies host an inner, secondary bar, the formation and evolution of double barred galaxies remain unclear. We show here an example model of a galaxy, dominated by a live dark matter halo, in which…
Using high resolution N-body simulations of stellar disks embedded in cosmologically motivated dark matter halos, we study the evolution of bars and the transfer of angular momentum between halos and bars. We find that dynamical friction…
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…
It has been known for some time that rotating bars in galaxies slow due to dynamical friction against the halo. However, recent attempts to use this process to place constraints on the dark matter density in galaxies and possibly also to…
We follow the formation and evolution of bars in N-body simulations of disc galaxies with gas and/or a triaxial halo. We find that both the relative gas fraction and the halo shape play a major role in the formation and evolution of the…
Elongated bar-like features are ubiquitous in galaxies, occurring at the centers of approximately two-thirds of spiral disks in the nearby Universe. Due to gravitational interactions between the bar and the other components of galaxies, it…
Stellar bars are the most common non-axisymmetric structures in galaxies and their impact on the evolution of disc galaxies at all cosmological times can be significant. Classical theory predicts that stellar discs are stabilized against…
`Conspiracy' between the dark and the baryonic mater prohibits an unambiguous decomposition of disc galaxy rotation curves into the corresponding components. Several methods have been proposed to counter this difficulty, but their results…
Galactic bars are found in the majority of disc galaxies. They rotate nearly rigidly with an angular frequency called pattern speed. Previous idealised simulations have shown that bar pattern speed decreases with time due to dynamical…
Resonant torques couple stellar bars to dark matter halos. Here we use high-resolution numerical simulations to demonstrate long-term angular momentum transfer between stellar bars and dark matter orbits of varying orientation. We show that…
Galaxy models have long predicted that galactic bars slow down by losing angular momentum to their postulated dark haloes. When the bar slows down, resonance sweeps radially outwards through the galactic disc while growing in volume,…
I follow a bar from its formation, via its evolution, to its destruction and, perhaps, regeneration. I discuss the main features at each stage and particularly the role of the halo. Bars can form even in sub-maximum discs. In fact, such…
The predicted central densities of dark matter halos in LCDM models exceed those observed in some galaxies. Weinberg & Katz argue that angular momentum transfer from a rotating bar in the baryonic disk can lower the halo density, but they…
The dynamic evolution of galactic bars in standard $\Lambda$CDM models is dominated by angular momentum loss to the dark matter haloes via dynamical friction. Traditional approximations to dynamical friction are formulated using the…
Bars in disk galaxies slow down as they transfer their angular momentum to their dark matter halo via dynamical friction from near-resonant orbits. This bar-halo dynamical friction can become ineffective once phase mixing erases the…
N-body simulations argue that the inner haloes of barred galaxies should not be spherical, nor even axisymmetric, but triaxial. The departure from sphericity is strongest near the centre and decreases outwards; typical axial ratios for the…
In this paper I argue that, far from necessarily hindering bar formation in disc galaxies, inner haloes may stimulate it. This constitutes a new instability mechanism by which bars can grow. To show this I use a number of N-body simulations…
We study the shape and kinematics of simulated dwarf galaxy discs in the APOSTLE suite of $\Lambda$CDM cosmological hydrodynamical simulations. We find that a large fraction of these gas-rich, star-forming discs show weak bars in their…
Bars and spiral arms have played an important role as constraints on the dynamics and on the distribution of dark matter in the optical parts of disk galaxies. Dynamics linked to the dissipative nature of gas, and its transformation into…