Related papers: Buckling instability in tidally induced galactic b…
We perform a linear magnetohydrodynamic perturbation analysis for a stratified magnetized envelope where the diffusion of heat is mediated by charged particles that are confined to flow along magnetic field lines. We identify an…
Secular evolution and fueling is driven by bars in spiral galaxies, and the related dynamical processes are reviewed. It is shown that gravity torques dominate over viscous torques, and produce gas infall to the center. In this infall, the…
It has been known for some time that the Milky Way is a barred disk galaxy. More recently several studies inferred from starcount observations that the Galaxy must contain a separate, new, flat long bar component, twisted relative to the…
Using hydrodynamic simulations, we investigate the physical properties of gaseous substructures in barred galaxies and their relationships with the bar strength. The gaseous medium is assumed to be isothermal and unmagnetized. The bar…
Using parsec-resolution simulations of a typical galaxy merger, we study the triggering of starbursts by connecting the (inter-)galactic dynamics to the structure of the interstellar medium. The gravitational encounter between two galaxies…
New JWST observations have revealed the presence of a significant number of high-redshift barred galaxies. The origin of these bars remains unclear, and their properties appear difficult to reconcile with the results of cosmological…
Although more than two-thirds of star-forming disk galaxies in the local universe are barred, some galaxies remain un-barred, occupying the upper half of the Hubble tuning fork diagram. Numerical simulations almost always produce bars…
Evidence for wave-like corrugations are well established in the Milky Way and in nearby disc galaxies. These were originally detected as a displacement of the interstellar medium about the midplane, either in terms of vertical distance or…
The secular evolution of disk galaxies is largely driven by resonances between the orbits of 'particles' (stars or dark matter) and the rotation of non-axisymmetric features (spiral arms or a bar). Such resonances may also explain kinematic…
Dynamical evolution of spiral galaxies is strongly dependent on non-axisymmetric patterns that develop from gravitational instabilities, either spontaneously or externally triggered. Some evolutionary sequences are described through which a…
The class `bulges' contains objects with very different formation and evolution paths and very different properties. I review two types of `bulges', the boxy/peanut bulges (B/Ps) and the discy bulges. The former are parts of bars seen…
The equilibrium state of a turbulent clumpy gas disk is analytically investigated. The disk consists of distinct self-gravitating clouds. Gravitational cloud-cloud interactions transfer energy over spatial scales and produce a viscosity,…
The assembly of the Milky Way bulge is an old topic in astronomy, one now in a period of renewed and rapid development. The dominant scenario for bulge formation is that of the Milky Way as a nearly pure disk galaxy, with the inner disk…
It is well established that bars evolve significantly after they form in galaxy discs, often changing shape both in and out of the disc plane. In some cases they may bend or buckle out of the disc plane resulting in the formation of…
Recent galaxy observations show that star formation activity changes depending on galactic environments. In order to understand the diversity of galactic-scale star formation, it is crucial to understand the formation and evolution of giant…
One of the scenarios for the formation of grand-design spiral arms in disky galaxies involves their interactions with a satellite or another galaxy. Here we consider another possibility, where the perturbation is instead due to the…
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…
Using numerical simulation, we study the development of gaseous inflows and triggering of starburst activity in mergers of comparable-mass disk galaxies. In all encounters studied, the galaxies experience strong gaseous inflows and moderate…
Simulations and observations of galactic bars suggest they do not commonly evolve into bulges, although it is possible that the earliest bars formed bulges long ago, when galaxies were smaller, denser, and had more gas. The most highly…
We present the latest development of the disk gravitational instability and fragmentation model, originally introduced by us to explain episodic accretion bursts in the early stages of star formation. Using our numerical hydrodynamics model…