We present a Chandra observation of the merging cluster of galaxies Abell 2744. The cluster shows strong evidence for an ongoing major merger which we believe to be responsible for the radio halo. X-ray emission and temperature maps of the cluster, combined with the spatial and redshift distribution of the galaxies, indicate a roughly north-south axis for the merger, with a significant velocity...

Using a simple model, we study the effects of turbulence on the motion of bubbles produced by AGN jet activities in the core of a galaxy cluster. We focus on the turbulence with scales larger then the size of the bubbles. We show that for a bubble pair with an age of ∼ 10 yr, the projected angle between the two vectors from the cluster center to the two bubbles should be & 90 and the ratio of t...

The energy loss of large molecular-hydrogen clusters incident on aluminum and amorphous carbon targets is analyzed as a function of the cluster size and velocity, using a dielectric formalism to describe the electronic interactions between the projectile and the target. The dependence of the energy loss with the cluster size predicts a marked different behavior for aluminum or amorphous carbon....

We study the dynamics and structure of clusters in the inhomogeneous clustered regime of a freely cooling granular gas of point particles in one dimension. The coefficient of restitution is modeled as r(0)<1 or 1, depending on whether the relative speed is greater or smaller than a velocity scale δ. The effective fragmentation rate of a cluster is shown to rise sharply beyond a δ-dependent time...

Various aspects of relativistic calculations of the Sunyaev-Zeldovich effect are explored and clarified. We first formally show that the main previous approaches to the calculation of the relativistically generalized thermal component of the effect are equivalent. Our detailed description of the full effect results in a somewhat improved formulation. Analytic approximations to the exact calcula...

Dust clusters, consisted of one up to twelve particles arranged in a horizontal plane, were formed in an inductively coupled rf plasma. When an axial magnetic field was applied to the dust clusters, the clusters rotate collectively in the left-handed direction with respect to the field. It was observed in our cluster rotation that, for single ring cluster, the angular velocity of the rotation i...

Near-future SZ surveys such as ACT, SPT, APEX, and Planck will soon find thousands of galaxy clusters. Multi-frequency arcminute-resolution SZ observations can, in principle, determine each cluster’s gas temperature (Te), bulk velocity (vpec), and optical depth (τ). However, the frequency bands and detector sensitivity employed by upcoming surveys will generally not be sufficient to disentangle...

We use the RASS-SDSS galaxy cluster sample to compare the quality of optical and X-ray luminosities as predictors of other cluster properties such as their masses, temperatures, and velocity dispersions. We use the SDSS spectroscopic data to estimate the velocity dispersions and the virial masses of a subsample of 69 clusters within r500 and r200. The ASCA temperature of the intracluster medium...

The kinematics of newly-formed star clusters are interesting both as a probe of the state of the gas clouds from which the stars form, and because they influence planet formation, stellar mass segregation, cluster disruption, and other processes controlled in part by dynamical interactions in young clusters. However, to date there have been no attempts to use simulations of star cluster formati...