Found 24 talks width keyword galactic kinematics

I will present new deep and wide narrow-band surveys undertaken with UKIRT, Subaru and the VLT; a unique combined effort to select large, robust samples of H-alpha (Ha) emitters at z=0.40, 0.84, 1.47 and 2.23 (corresponding to look-back times of 4.2, 7.0, 9.2 and 10.6 Gyrs) in a uniform manner over ~2 sqdeg in the COSMOS and UDS fields. The deep multi-epoch Ha surveys are sensitive to Milky-Way SFRs out to z=2.2 for the first time, while the wide area and the coverage over two independent fields allows to greatly overcome cosmic variance. A total of over 600 sources per epoch are homogeneously selected. Overall, the evolution seen in Ha is in good agreement with the evolution seen using inhomogeneous compilations of other tracers of star formation, such as FIR and UV, jointly pointing towards the bulk of the evolution in the last 11 Gyrs being driven by a strong luminosity/SFR increase from z~0 to z~2.2. Our uniform analysis allows to derive the Ha star formation history of the Universe, for which a simple time-parametrisation is a good approximation for the last 11Gyrs. Both the shape and normalisation of the Ha star formation history are consistent with the measurements of the stellar mass density growth, confirming that our Ha analysis traces the bulk of the formation of stars in the Universe up to z~2.2. We are also exploring the large, multi-epoch and homogeneously selected samples of Ha emitters to conduct detailed morphology, dust, clustering, environment and mass studies which are providing us with a unique view on the evolution of star-forming galaxies and what has been driving it for the past 11 Gyrs.

We find a distinct stellar population in the counterrotating and kinematically decoupled core of the isolated massive elliptical galaxy NGC 1700. Coinciding with the edge of this core, we find a significant change in the slope of the gradient of various representative absorption line indices. Our age estimate for this core is markedly younger than the main body of the galaxy. We find lower values for the age, metallicity, and Mg/Fe abundance ratio in the center of this galaxy when we compare them with other isolated elliptical galaxies with similar velocity dispersion. We discuss the different possible scenarios that might have lead to the formation of this younger kinematically decoupled structure and conclude that, in light of our findings, the ingestion of a small stellar companion on a retrograde orbit is the most favored.

Dark Matter in Galaxies is an important subject of current astrophysical research. I will concentrate on spiral galaxies, and first give an overview of the subject from the standpoint of a radioastronomer with a long involvement in the subject. This includes a historical introduction and a review of some of the present-day debates. The currently popular Lambda-CDM model has problems on the scale of galaxies. In a second part I will address more specifically the problem that we still do not know how much dark matter there is in spiral galaxies, and how it is distributed. This is due to the fact that the M/L of the visible matter is poorly constrained and that there is a 'conspiracy' between the dark and the baryonic material. I will present various dynamical methods that have been proposed to constrain the dark matter mass distribution and discuss their advantages and disadvantages.

Two-dimensional stellar kinematics obtained with the integral-field spectrograph SAURON allow the classification of early-type galaxies into 'slow' and 'fast' rotators, different from their morphological classification into ellipticals and lenticulars. Most fast rotators, including lenticular as well as many elliptical galaxies, are consistent with oblate axisymmetric disk-like systems. On the other hand, the slow-rotator ellipticals show clear deviations from axisymmetry, which can be modeled with our extension of Schwarzschild's orbit superposition method to triaxial geometry. Besides galaxies, I show that Schwarzschild's method can also be used to model in detail globular clusters such as ω Cen and M15. The recovered internal orbital structure of ω Cen reveals besides a signature of tidal interaction, also a central stellar disk, supporting its origin as the nucleus of a stripped dwarf galaxy. The formally best-fit Schwarzschild model for M15 includes an intermediate-mass black hole, but we cannot exclude a model in which dark remnants make up the dark mass in the collapsed core.