We analyze the internal velocity dispersion, σ, of a sample of 172 nearby galaxy clusters (z≤ 0.15), each of which has at least 30 available galaxy redshifts, and spans a large richness range. Cluster membership selection is based on nonparametric methods. In the estimate of galaxy velocity dispersion we consider the effects of possible velocity anisotropies in galaxy orbits, the infall of late...

We propose a new approach to study the dynamical implications of mass models of clusters for the velocity structure of galaxies in the core. Strong and weak lensing data are used to construct the total mass profile of the cluster, which is used in conjunction with the optical galaxy data to solve in detail for the nature of galaxy orbits and the velocity anisotropy in the central regions. We al...

Granular gases present novel challenges, previously not encountered in fluid dynamics [1]. Specifically, the strong underlying energy dissipation leads to clustering instabilities and strong velocity correlations [2–7]. A series of recent experimental and theoretical studies reveals a rich phenomenology. In particular, velocities are characterized by anomalous statistics, sensitive to the detai...

We present an approach based on clustering to segment renal arteries from 2D PC Cine MR images to measure blood velocity and flow. Such information are important in grading renal artery stenosis and support the decision on surgical interventions like percutan transluminal angioplasty. Results show that the renal arteries could be extracted automatically and the corresponding velocity profiles c...

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 examine the internal dynamics and caustic structure of the rich cluster A1689, combining VLT/VIMOS spectroscopy with Subaru/Suprime-Cam imaging. The radial velocity distribution of ∼ 500 cluster members is bounded by a pair of clearly defined velocity caustics, with a maximum amplitude of ∼ |4000| km/s at ≃ 300 h kpc, beyond which the amplitude steadily declines, meeting at zero velocity at ...

We study luminosity and morphology segregation of cluster galaxies in an ensemble cluster built from 59 rich, nearby galaxy clusters observed in the ESO Nearby Cluster Survey (ENACS). The ensemble cluster contains 3056 member galaxies with positions, velocities and magnitudes ; 96% of these also have galaxy types. From positions and velocities we identify galaxies within substruc-tures, viz. as...

We propose the thermodynamic Cucker–Smale system with unit-speed constraints (TCSUS) and study its emergent dynamics rigorous proofs. For this, three dissipative differential inequalities are derived in terms of $ L^\infty $-diameters position–velocity–temperature to verify mono-cluster flocking TCSUS model under suitable frameworks using two approaches. Motivated by first approach, we provide ...

Small number statistics may heavily affect the structure of the broadening function in integrated spectra of galactic globular cluster centers. As a consequence, it is a priori unknown how closely line broadening measurements gauge the intrinsic velocity dispersions at the cores of these stellar systems. We have tackled this general problem by means of Monte Carlo simulations. An examination of...