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We present a statistical study of optical warps in a sample of 540 galaxies, about five times larger than previous samples. About 40% of all late-type galaxies reveal S-shaped warping of their planes in the outer parts. Given the…
We present deep optical long-slit spectra of 17 edge-on spiral galaxies of intermediate to late morphological type, mostly parallel to their major axes and in a few cases parallel to the minor axes.The line-of-sight stellar kinematics are…
We analyze bars formed in $N$-body simulations to investigate two key aspects of stellar kinematic structure of barred galaxies: the angular distributions of the radial and azimuthal components of stellar velocities, and the impact of bars…
It has been proposed that the flat rotation curves observed at large radii in disk galaxies can be interpreted as an effect of General Relativity (GR) instead of the presence of dark matter (DM) halos in Newtonian gravity. In Ciotti (2022)…
Advances in instrumentation have recently extended detailed measurements of gas kinematics to large samples of high-redshift galaxies. Relative to most nearby, thin disk galaxies, in which gas rotation accurately traces the gravitational…
Previous analyses of large databases of Milky Way stars have revealed the stellar disk of our Galaxy to be warped and that this imparts a strong signature on the kinematics of stars beyond the solar neighborhood. However, due to the…
We consider the most commonly occurring circumstances which apply to galaxies, namely membership in galaxy groups of about $10^{13}h^{-1} M_\odot$ total mass, and estimate the accompanying physical conditions of intergalactic medium (IGM)…
We have examined the trend between CO and HI linewidths by compiling the linewidths of 219 nearby galaxies. The trend is that the CO linewidths of fast rotating galaxies tend to be larger than the HI linewidths, and that the HI linewidths…
The Milky Way disc presents a warp, a flare, lopsidedness and other deviations from a purely axisymmetrical double exponential density component, both for the stellar and the gas component. Moreover, recent large-scale extended kinematics…
A technique is introduced for deriving the gaseous rotation curves of edge-on spiral galaxies. The entire major axis position-velocity (XV) diagram is modeled with a set of rings in a least-squares sense, allowing for the effects of…
The Milky Way's neutral hydrogen (HI) disk is warped and flared. However, a dearth of accurate HI-based distances has thus far prevented the development of an accurate Galactic disk model. Moreover, the extent to which our Galaxy's stellar…
Some 30% of disc galaxies have a pronounced central bar feature in the disc plane and many more have weaker features of a similar kind. Kinematic data indicate that the bar constitutes a major non-axisymmetric component of the mass…
Recent cosmological hydrodynamical simulations suggest that integral field spectroscopy can connect the high-order stellar kinematic moments h3 (~skewness) and h4 (~kurtosis) in galaxies to their cosmological assembly history. Here, we…
In this paper we study long slit spectra in the region of H$\alpha$ emission line of a sample of 111 spiral galaxies with recognizable and well defined spiral morphology and with a well determined environmental status, ranging from…
A substantial fraction of the warps in spiral galaxies may result from bending instabilities if the disks are essentially self-gravitating. With N-body simulations, we show that galaxies with self-gravitating disks as thick as HI disks are…
To understand the processes that build up galaxies we investigate the stellar structure and gas kinematics of spiral and irregular galaxies out to redshift 1. We target 92 galaxies in four cluster (z = 0.3 & 0.5) fields to study the…
Context: Warps occurring in galactic discs have been studied extensively in HI and in the optical, but rarely in the near-infrared (NIR) bands that trace the older stellar populations. Aims: We provide NIR data of nearby edge-on galaxies,…
(Abridged). It has been recently shown that random motions of the neutral Hydrogen gas of the Triangulum galaxy (M33) exhibit a bisymmetric perturbation which is aligned with the minor axis of the galaxy, suggesting a projection effect. To…
We investigate the resolved kinematics of the molecular gas, as traced by ALMA in CO (2-1), of 25 cluster member galaxies across three different clusters at a redshift of $z\sim1.6$. This is the first large-scale analysis of the molecular…
We have explored the galaxy disk/extended halo gas kinematic relationship using rotation curves (Keck/ESI) of ten intermediate redshift galaxies which were selected by MgII halo gas absorption observed in quasar spectra. Previous results of…