Using a combination of Chandra and XMM observations, we confirmed the presence of a significant velocity gradient along the NE/E–W/SW direction in the intracluster gas of the cluster Abell 576. The results are consistent with a previous ASCA SIS analysis of this cluster. The error weighted average over ACIS-S3, EPIC MOS 1 & 2 spectrometers for the maximum velocity difference is >3.3×10 km s−1 a...

We propose a test that can in principle detect any systematic errors in the Hipparcos parallaxes towards the Hyades cluster at the level of 0.3 mas. We show that the statistical parallax algorithm subsumes the classical moving cluster methods and provides more precise estimates of the distance and the first two moments of the velocity distribution of the Hyades cluster namely, its bulk space ve...

The local solid flow structure of gas-solid bubbling fluidized bed was investigated to identify and characterize the particle clusters. Extensive mathematical calculations were carried out using the energy-minimization multi-scale (EMMS) approach for evaluating cluster properties including the velocity, the size and the void fraction of clusters in the dense phase of the bed. The results showed...

We determine the velocity correlation function, pairwise peculiar velocity di erence, and root-mean-square pairwise peculiar velocity dispersion of rich clusters of galaxies, as a function of pair separation, for three cosmological models: = 1 and = 0:3 CDM, and = 0:3 PBI models (all at and COBEnormalized). We nd that close cluster pairs, with separation r 10h 1Mpc, exhibit strong attractive pe...

Future microwave sky surveys will have the sensitivity to detect the kinematic Sunyaev-Zeldovich signal from moving galaxy clusters, thus providing a direct measurement of their line-of-sight peculiar velocity. We show that cluster peculiar velocity statistics applied to foreseeable surveys will put significant constraints on fundamental cosmological parameters. We consider three statistical qu...

The distribution of galaxies in position and velocity around the centers of galaxy clusters encodes important information about cluster mass and structure. Using the maxBCG galaxy cluster catalog identified from imaging data obtained in the Sloan Digital Sky Survey, we study the BCG–galaxy velocity correlation function. By modeling its non-Gaussianity, we measure the mean and scatter in velocit...

We compare the cumulative distribution of internal velocity dispersions of galaxy clusters,N(> σv), for a large observational sample to those obtained from a set of N– body simulations that we run for seven COBE–normalized cosmological scenarios. They are: the standard CDM (SCDM) and a tilted (n = 0.85) CDM (TCDM) model, a cold+hot DM (CHDM) model with Ων = 0.25, two low–density flat CDM (ΛCDM)...