Related papers: Galactic mapping with general relativity and the o…
I discuss measurements of disk mass from non-circular streaming motions of gas in the barred galaxies NGC 3095 and NGC 4123. In these galaxies with strong shocks and non-circular motions, the inner regions must be disk-dominated to…
Large surveys of the local Universe have shown that galaxies with different intrinsic properties, such as colour, luminosity and morphological type display a range of clustering amplitudes. Galaxies are therefore not faithful tracers of the…
The inner ~200 pc region of the Milky Way contains a nuclear stellar disc and a nuclear star cluster that are embedded in the larger Galactic bar. These stellar systems overlap spatially, which makes it challenging to separate stars that…
Observed mass-to-light ratios (M/L) of metal-rich globular clusters (GCs) disagree with theoretical predictions. This discrepancy is of fundamental importance since stellar population models provide the stellar masses that underpin most of…
We present evidence for a Galactic North-South asymmetry in the number density and bulk velocity of solar neighborhood stars. The number density profile, which is derived from main-sequence stars in the Sloan Digital Sky Survey, shows a…
Our Milky Way Galaxy is a typical large spiral galaxy, representative of the most common morphological type in the local Universe. We can determine the properties of individual stars in unusual detail, and use the characteristics of the…
According to the standard model of cosmology, galaxies are embedded in dark matter halos which are made of particles beyond the standard model of particle physics, thus extending the mass and the size of the visible baryonic matter by…
Modified Newtonian dynamics (MOND) and similar proposals can (at least partially) explain the excess rotation of galaxies or the equivalent mass-discrepancy acceleration, without (or by reducing) the requirement of dark matter halos. This…
We present the result of a comparison between the dark matter distribution inferred from weak gravitational lensing and the observed galaxy distribution to identify dark structures with a high dark matter-to-galaxy density ratio. To do…
We investigate the possibility that the observed rotation of galaxies can be accounted for by invoking a massive baryonic disc with no need for non-baryonic dark matter or a massive halo. There are 5 primary reasons for suggesting this: 1.…
The dark matter constraint imposed by the recent WMAP experiment on gravitational theories is analyzed. Using the non-linearity of the vacuum Einstein's equations, it is shown that when the slow motion condition is applied to the geodesic…
In Milgrom's modified Newtonian dynamics (MOND) framework, the dynamical mass of a galaxy is fully determined by its baryonic matter distribution. We fit the distribution of cold and hot gas halos, focusing on hot gas, around SDSS central…
Masses of galaxies are beginning to be measured systematically at redshifts z > 0.3. Such data provide powerful and unique links and clues to theories, simulations, and our understanding of early galaxy formation and evolution.…
I review some recent results about the molecular content of galaxies, obtained essentially from the CO lines, but also dense tracers, or the dust continuum emission. New results have been obtained on molecular cloud physics, and their…
For 18 well-observed gravitationally lensed QSOs, we compare new non-parametric mass profiles for the lensing galaxies with stellar-population models derived from published HST photometry. The large volume of parameter space searched --…
There is strong evidence that the mass in the Universe is dominated by dark matter, which exerts gravitational attraction but whose exact nature is unknown. In particular, all galaxies are believed to be embedded in massive haloes of dark…
We describe a powerful technique to model and interpret the stellar line-of-sight velocity profiles of galaxies. Following Schwarzschild's modeling approach, a representative library of orbits is calculated in a given potential; then the…
I present some new results related to our understanding of the masses of galaxies both in the local and high-redshift Universe. At high-redshift new Spitzer data on galaxies in the Gemini Deep Deep Survey allow us a more accurate measure of…
Stellar streams have proven to be powerful tools for measuring the Milky Way's gravitational potential and hence its dark matter halo. In the coming years, Vera Rubin, Euclid, ARRAKIHS, and NGRST will uncover a plethora of streams around…
The mass function of galaxies and clusters of galaxies can be derived observationally based on different types of observations. In this study we test if these observations can be combined to a consistent picture which is also in accord with…