Related papers: Effects of galaxy-halo alignment and adiabatic con…
We study the statistics of large-separation gravitational lens systems produced by non-spherical halos in the Cold Dark Matter (CDM) model. Specifically, we examine how the triaxiality of CDM halos affects the overall lensing probabilities…
We present theoretical and observational studies of strong gravitational lenses produced by clusters of galaxies. Our purpose is to test the Cold Dark Matter (CDM) model at small and highly non-linear scales where it has been claimed that…
Measuring the distribution of mass on galaxy cluster scales is a crucial test of the Lambda CDM model, providing constraints on the nature of dark matter. Recent work investigating mass distributions of individual galaxy clusters using…
Strong lensing is a powerful probe of the distribution of matter in the cores of clusters of galaxies. Recent studies suggest that the cold dark matter model predicts cores that are denser than those observed in galaxies, groups and…
We use the semi-analytical approach to analyze gravitational lensing of quasars by dark halos in various cold dark matter (CDM) cosmologies, in order to determine the sensitivity of the prediction probabilities of images separations to the…
Measuring the 3D distribution of mass on galaxy cluster scales is a crucial test of the LCDM model, providing constraints on the nature of dark matter. Recent work investigating mass distributions of individual galaxy clusters (e.g. Abell…
We study the profiles of 75 086 elliptical galaxies from the Sloan Digital Sky Survey (SDSS) at both large (50-500 kpc/h) and small (~3 kpc/h) scales. Weak lensing observations in the outskirts of the halo are combined with measurements of…
We use a semi-empirical model to investigate the radial acceleration relation (RAR) in a cold dark matter (CDM) framework. Specifically, we build 80 model galaxies covering the same parameter space as the observed galaxies in the SPARC…
Formation of sub-galactic halos is suppressed in warm dark matter (WDM) model due to thermal motion of WDM particles. This may provide a natural resolution to some puzzles in standard cold dark matter (CDM) theory such as the cusped density…
The cold dark matter scenario predicts that a large number of dark subhalos should be located within the halo of each Milky-way sized galaxy. One tell-tale signature of such dark subhalos could be additional milliarcsecond-scale image…
We study lens statistics in flat, low-density universes with different equations of state $w=p_Q/\rho_Q$ for the dark energy component. Dark energy modifies the distance-redshift relation and the mass function of dark matter halos leading…
N-body simulations and analytical calculations of the gravitational collapse in an expanding universe predict that halos should form with a diverging inner density profile, the cusp. There are some observational indications that the dark…
The distribution of mass on galaxy cluster scales is an important test of structure formation scenarios, providing constraints on the nature of dark matter itself. Several techniques have been used to probe the mass distributions of…
We present the results of a study of the average mass profile around galaxies using weak gravitational lensing. We use 45.5 deg^2 of R_C band imaging data from the Red-Sequence Cluster Survey (RCS) and define a sample of 1.2\times 10^5…
The lensing cross section of triaxial halos depends on the relative orientation between a halo's principal axes and its line of sight. Consequently, a lensing subsample of randomly oriented halos is not, in general,randomly oriented. Using…
We investigate structural properties of dark matter halos of disk galaxies in LCDM cosmology, using a well-defined sample of 81 disk-dominated galaxies from the SDSS redshift survey. We model the mass-velocity and fundamental plane…
We have used a combination of high resolution cosmological N-body simulations and semi-analytic modelling of galaxy formation to investigate the processes that determine the spatial distribution of galaxies in cold dark matter (CDM) models.…
We present the results of a study of weak lensing by galaxies based on 45.5 deg$^2$ of $R_C$ band imaging data from the Red-Sequence Cluster Survey (RCS). We present the first weak lensing detection of the flattening of galaxy dark matter…
Statistics of lensed arcs in clusters of galaxies serve as a powerful probe of both the non-sphericity and the inner slope of dark matter halos. We develop a semi-analytic method to compute the number of arcs in triaxial dark matter halos.…
We analyse the impact of galaxy--halo misalignment on the ability of weak lensing studies to constrain the shape of dark matter haloes, using a combination of the Millennium dark matter N-body simulation and different semi-analytic galaxy…