Related papers: Dynamical Stability and Environmental Influences i…
We use a model of galaxy disk formation to explore the metallicities, dust content, and neutral-gas mass density of damped Lyman-$\alpha$ (D\lya) absorbers. We find that the [Zn/H] abundance measurements of D\lya systems now available can…
A bar rotating in a pressure-supported halo generally loses angular momentum and slows down due to dynamical friction. Valenzuela & Klypin report a counter-example of a bar that rotates in a dense halo with little friction for several Gyr,…
We calculate the stellar surface mass density (Sigma_*) and two-component (gas+stars) disk stability (Q_RW) for 25 late-type galaxies from the DiskMass Survey. These calculations are based on fits of a dynamical model to our ionized-gas and…
Rare giant low surface brightness galaxies (gLSBGs) act as a stress test for the current galaxy formation paradigm. To answer the question `How rare are they?' we estimate their volume density in the local Universe. A visual inspection of…
We examine the bar instability in galactic models with an exponential disk and a cuspy dark matter (DM) halo with a Navarro-Frenk-White (NFW) cosmological density profile. We construct equilibrium models from a 3-integral composite…
Lyman break galaxies (LBGs) at $z \sim 3$ exhibit number densities and clustering similar to local $L_*$ galaxies; however, their star formation rates (SFRs) are much higher. We explore the scenario in which LBGs are starburst galaxies…
The stability of a recently proposed general relativistic model of galaxies is studied in some detail. This model is a general relativistic version of the well known Miyamoto-Nagai model that represents well a thick galactic disk. The…
We study the dynamical stability against bar-mode deformation of rapidly and differentially rotating stars in the first post-Newtonian approximation of general relativity. We vary the compaction of the star $M/R$ (where $M$ is 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…
Giant low surface brightness galaxies (gLSBGs) with dynamically cold stellar discs reaching the radius of 130 kpc challenge currently considered galaxy formation mechanisms. We analyse new deep long-slit optical spectroscopic observations,…
A significant fraction of nearby elliptical galaxies are known to have high density gas disks in their circumnuclear (CN) region (0.1 to a few kpc). Yet, ellipticals, especially luminous ones, show little signs of recent star formation…
Gravitational instabilities play an important role in galaxy evolution and in shaping the interstellar medium (ISM). The ISM is observed to be highly turbulent, meaning that observables like the gas surface density and velocity dispersion…
While bright, blue, compact galaxies are common at $\rm z \sim 1$, they are relatively rare in the local universe, and their evolutionary paths are uncertain. We have obtained resolved H I observations of nine $\rm z \sim 0$ luminous…
We analyze a clean sample of 1,118 late-type, face-on galaxies without AGN contamination from the MaNGA survey. Their photometric structures are quantified via two-component (bulge+disk) decompositions on deep $g$-band images from the DESI…
We investigate the dependence of occurrence of bars in galaxies on galaxy properties and environment. We use a volume-limited sample of 33,391 galaxies brighter than $M_{r}=-19.5+5$log$h$ at $0.02\le z\le0.05489$, drawn from the SDSS DR 7.…
We examine the global stability of an exponential stellar disk embedded in a dark matter halo and constrain the mass-to-light ratio of observed disks in the I-band, Y_I. Assuming only that the radial surface density distribution of disks is…
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…
Low mass surface density spiral and irregular galaxies like low surface brightness (LSB) and dwarf galaxies are unique laboratories to study the dynamical properties of Dark Matter halos because their mass is generally dominated by dark…
We derive the evolution equations describing a thin axisymmetric disk of gas and stars with an arbitrary rotation curve that is kept in a state of marginal gravitational instability and energy equilibrium due to the balance between energy…
Thermal emission from a rotating, supermassive star will cause the configuration to contract slowly and spin up. If internal viscosity and magnetic fields are sufficiently weak, the contracting star will rotate differentially. For each of…