Related papers: Galactic disks as reaction-diffusion systems
(Abridged). We model gravitational instability in a wide range of isolated disk galaxies, using GADGET, a three-dimensional, smoothed particle hydrodynamics code. The model galaxies include a dark matter halo and a disk of stars and…
We discuss the main ingredients necessary to build models of chemical evolution of spiral galaxies and in particular the Milky Way galaxy. These ingredients include: the star formation rate, the initial mass function, the stellar yields and…
Self-gravitating systems evolve toward the most tightly bound configuration that is reachable via available evolution processes. The inner parts shrink and the outer parts expand, provided that some physical process transports energy or…
After a recall of fundamental concepts used in galactic dynamics, we review observational facts as well as results of orbit theory and numerical simulations which suggest long-term evolution of galaxies. Dynamical interactions between…
After their initial formation, disk galaxies are observed to be rotationally stable over periods of >6 Gyr, implying that any large velocity disturbances of stars and gas clouds are damped rapidly on the timescale of their rotation.…
The abundance gradients and the radial gas profile of the Galactic disc are analysed by means of a model for the chemical evolution of galaxies. As one of the major uncertainties in models for galaxy evolution is the star formation (SF)…
Gas-rich disks in the early universe are highly turbulent and have giant star-forming clumps. Models suggest the clumps form by gravitational instabilities, and if they resist disruption by star formation, then they interact, lose angular…
The stability of thin homogeneous gaseous disk with step discontinuity of velocity and density profile has been investigated analytically in the limitary case of large compressibility and numerically at spatially separated velocity and…
The formation of disk galaxies is one of the most outstanding problems in modern astrophysics and cosmology. We review the progress made by numerical simulations carried out on large parallel supercomputers. Recent progress stems from a…
We adopt a scenario in which the Galactic thick disk was formed by minor merging between the first generation of the Galactic thin disk (FGTD) and a dwarf galaxy about 9 Gyr ago and thereby investigate chemical and dynamical properties of…
This paper reports simulations allowing for stochastic accretion and mass loss within closed and open systems modeled using a previously developed multi-population, multi-zone (halo, thick disk, thin disk) treatment. The star formation rate…
The manner the galaxy accretes matter along with the star formation rates at different epochs, influence the evolution of the stable isotopic inventories of the galaxy. A detailed analysis is presented here to study the dependence of the…
We present results of numerical modeling made for the galactic stellar disk embedded in the spherical halo. The non-linear dynamics of bending instabilities developed in the disk is studied. The axisymmetrical bending mode is considered as…
We examine the tidal disruption of satellite galaxies in a cosmological simulation of the formation of a disk galaxy in the $\Lambda$CDM scenario. We find that the disruption of satellite galaxies in orbits roughly coplanar with the disk…
I critically discuss in a pedagogical and phenomenological way a few crucial tests challenging the claims by Pietronero and collaborators that there is no evidence from available galaxy catalogues that the Universe is actually homogeneous…
The disk galaxy simulated using our chemo-dynamical galaxy formation code, GCD+, is shown to have a thick disk component. This is evidenced by the velocity dispersion versus age relation for solar neighbourhood stars, which clearly shows an…
The saturation conditions for bending modes in inhomogeneous thin stellar disks that follow from an analysis of the dispersion relation are compared with those derived from $N$-body simulations. In the central regions of inhomogeneous…
A large fraction of bulgeless disk galaxies contain young compact stellar systems at their centers, in spite of the local gravitational stability of these disks. We evaluate two contrasting hypotheses for the origin of the nuclear star…
One of the outstanding puzzles about star formation is why it proceeds so slowly. Giant molecular clouds convert only a few percent of their gas into stars per free-fall time, and recent observations show that this low star formation rate…
The disks of spiral galaxies commonly show a lopsided mass distribution, with a typical fractional amplitude of 10 % for the Fourier component m=1. This is seen in both stars and gas, and the amplitude is higher by a factor of two for…