Related papers: The offsets between galaxies and their dark matter…
We extend our analyses of the dark matter (DM) distribution in relaxed clusters to the case of Abell 383, a luminous X-ray cluster at z=0.189 with a dominant central galaxy and numerous strongly-lensed features. Following our earlier…
Observations of compact groups of galaxies (CGs) indicate that their abundance has not significantly changed since $z=0.2$. This balance between the timescales for formation and destruction of CGs is challenging if the typical timescale for…
We present a comprehensive study on how perturbations due to a distribution of $\Lambda$CDM dark matter subhalos can lead to star clusters deviating from their orbits. Through a large suite of massless test particle simulations, we find…
We study the luminosity gap, dm12, between the first and second ranked galaxies in a sample of 59 massive galaxy clusters, using data from the Hale Telescope, HST, Chandra, and Spitzer. We find that the dm12 distribution, p(dm12), is a…
We analyze the structure of the X-ray emission of a sample of 22 Abell clusters of galaxies with a cD in their centre, observed with the ROSAT PSPC. Utilizing the multi-scale power of the Wavelet Transform we detect significant (~ 50 h^{-1}…
We investigate galaxy clustering and galaxy-mass correlations in the LCDM cosmological model using a large volume SPH simulation. For the most part, the predicted biases between galaxies and dark matter lead to good agreement with current…
If dark matter has a large self-interaction scattering cross section, then interactions among dark-matter particles will drive galaxy and cluster halos to become spherical in their centers. Work in the past has used this effect to rule out…
The leading tensions to the collisionless cold dark matter (CDM) paradigm are the "small-scale controversies", discrepancies between observations at the dwarf-galactic scale and their simulational counterparts. In this work we consider…
We compare new maps of the hot gas, dark matter, and galaxies for 1E0657-56, a cluster with a rare, high-velocity merger occurring nearly in the plane of the sky. The X-ray observations reveal a bullet-like gas subcluster just exiting the…
N-body simulations were conducted of pairs of galaxies with a 3:1 mass ratio on parabolic orbits, in order to quantify the effect of dynamical friction. The effects of varying the ratio of the dark matter halo size to the distance of…
Accurate knowledge of the morphology of halos and its evolution are key constraints on the galaxy formation model as well as a determinant parameter of the strong-lensing phenomenon. Using the cosmological hydrodynamic simulation, the…
We confirm at the $5.7\sigma$ level previous studies reporting Cosmic Microwave Background (CMB) temperatures being significantly lower around nearby spiral galaxies than expected in the $\Lambda$CDM model. Results from our earlier work was…
Parametric strong lensing studies of galaxy clusters often display misleading features: group/cluster scale dark matter components without any stellar counterpart, offsets between both components larger than what might be allowed by neither…
Using a resimulation technique, we perform high-resolution cosmological simulations of dry mergers in a massive galaxy cluster identified in the Millennium Run. Our initial conditions include well resolved compound galaxy models consisting…
Recently, an extension of the geodesic equations of motion using the Dark Energy length scale was proposed. Here, we apply this extension to the analyzing the motion of test particles at the galactic scale and longer. A cosmological check…
We use high resolution simulations to study the formation and distribution of galaxies within a cluster which forms hierarchically. We follow both dark matter and baryonic gas which is subject to thermal pressure, shocks and radiative…
How do observed voids relate to the underlying dark matter distribution? To examine the spatial distribution of dark matter contained within voids identified in galaxy surveys, we apply Halo Occupation Distribution models representing…
We give a summary of recent results on spatial and velocity biases in cosmological models. Progress in numerical techniques made it possible to simulate halos in large volumes with a such accuracy that halos survive in dense environments of…
We investigate the mass content of galaxies in the core of the galaxy cluster Abell 611. We perform a strong lensing analysis of the cluster core and use velocity dispersion measurements for individual cluster members as additional…
We have performed a series of N-body experiments on Connection Machine-5 in order to simulate the formation of galaxy clusters gravitationally dominated by a massive dark background. In accordance with previous authors we find an extremely…