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3D-Particle Tracking (3D-PTV) and Phase Sensitive Constant Temperature Anemometry in pseudo-turbulence--i.e., flow solely driven by rising bubbles-- were performed to investigate bubble clustering and to obtain the mean bubble rise…

Fluid Dynamics · Physics 2012-11-14 J. Martinez , D. Chehata , D. P. M. van Gils , C. Sun , D. Lohse

We present cosmological constraints from measurements of the gas mass fraction, $f_{gas}$, for massive, dynamically relaxed galaxy clusters. Our data set consists of Chandra observations of 40 such clusters, identified in a comprehensive…

The recently approved COBRAS/SAMBA cosmic microwave background mission will also have a major impact on measurements of the Sunyaev-Zeldovich effect. The frequency of three of the channels (150 GHz, 217 GHz, 353 GHz) are chosen to optimize…

Astrophysics · Physics 2007-05-23 Martin G. Haehnelt

We present the analysis of a local (z = 0.04 - 0.2) sample of 31 galaxy clusters with the aim of measuring the density of the X-ray emitting gas in cluster outskirts. We compare our results with numerical simulations to set constraints on…

Cosmology and Nongalactic Astrophysics · Physics 2015-10-08 D. Eckert , F. Vazza , S. Ettori , S. Molendi , D. Nagai , E. T. Lau , M. Roncarelli , M. Rossetti , S. L. Snowden , F. Gastaldello

We present radio continuum observations of the spiral-shaped ionized feature (Sgr A West) within the inner pc of the Galactic center at three epochs spanning 1986 to 1995. The VLA A-configuration was used at $\lambda$2cm (resolution of…

Astrophysics · Physics 2016-08-30 F. Yusef-Zadeh , D. A. Roberts , J. Biretta

In order to study the nature, origin, and impact of turbulent velocity fluctuations in the ionized gas of the Orion Nebula, we apply a variety of statistical techniques to observed velocity cubes. The cubes are derived from high resolving…

Astrophysics of Galaxies · Physics 2016-09-07 S. J. Arthur , S. -N. X. Medina , W. J. Henney

We re-examine the X-ray luminosity-temperature relation using a nearly homogeneous data set of 24 clusters selected for statistically accurate temperature measurements and absence of strong cooling flows. The data exhibit a remarkably tight…

Astrophysics · Physics 2009-10-30 Monique Arnaud , August E. Evrard

We report spectral analysis on a 170 ks XRISM \textit{Resolve} exposure of the core of Cygnus A. Analyzing the full field of view spectrum in the $1.7-12.0$ keV band, we find evidence for two-temperature cluster gas. The hotter ($kT = 5.53…

High Energy Astrophysical Phenomena · Physics 2025-12-12 Anwesh Majumder , T. Heckman , J. Meunier , A. Simionescu , B. R. McNamara , L. Gu , A. Ptak , E. Hodges-Kluck , M. Yukita , M. W. Wise , N. Roy

We present Ginga measurements of the spatial fluctuations in the diffuse X-ray background. When combined with earlier results, the new data constrain the extragalactic log N - log S relation in the 2-10 keV energy band to a form close to…

In the hierarchical structure formation model, clusters of galaxies form through a sequence of mergers and continuous mass accretion, which generate significant random gas motions especially in their outskirts where material is actively…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-16 Daisuke Nagai , Erwin T. Lau , Camille Avestruz , Kaylea Nelson , Douglas H. Rudd

An atlas of gas temperature maps is presented for a flux limited catalog of galaxy clusters. The sample of clusters is based on the Edge et al. (1990) sample, with the inclusion of five additional clusters, all with fluxes f_X(2-10 keV)>=…

Astrophysics · Physics 2007-05-23 R. Hank Donnelly , C. Jones , W. Forman , E. Churazov , M. Gilfanov

We have used the ARGUS multi-object spectrometer at the CTIO 4m Blanco telescope to obtain 2756 radial velocity measurements for 1966 individual stars in the globular cluster omega Centauri brighter than blue photographic magnitude of about…

The galaxy cluster Zwicky 3146 is a sloshing cool core cluster at $z{=}0.291$ that in SZ imaging does not appear to exhibit significant pressure substructure in the intracluster medium (ICM). We perform a surface brightness fluctuation…

We have carried out a study of the velocity dispersion of the stars in the outskirts of the globular cluster Omega Centauri, finding that the velocity dispersion remains constant at large radii rather than decrease monotonically. The…

Astrophysics · Physics 2011-05-23 Riccardo Scarpa , Gianni Marconi , Roberto Gilmozzi

By combining galaxy tracers from high-resolution N-body and hydrodynamical simulations, we present a consistent picture of the behaviour of galaxy velocities in massive clusters. In haloes above ~ 10^14 Msun, the brightest satellite…

Cosmology and Nongalactic Astrophysics · Physics 2013-09-20 Hao-Yi Wu , Oliver Hahn , August E. Evrard , Risa H. Wechsler , Klaus Dolag

The nature of our Milky Way Galaxy is reexamined from an eclectic point of view. Evidence for a central bar, for example, is not reflected in the distribution of RR Lyrae variables in the central bulge [4,5], and it is not clear if either a…

Astrophysics of Galaxies · Physics 2015-06-17 David G. Turner

We study the formation and the dynamics of correlations in the velocity field for 1D and 2D cooling granular gases with the assumption of negligible density fluctuations (``Homogeneous Velocity-correlated Cooling State'', HVCS). It is shown…

Statistical Mechanics · Physics 2015-06-24 Andrea Baldassarri , Umberto Marini Bettolo Marconi , Andrea Puglisi

We report our analysis of the properties of galaxy clustering for a new redshift sample of galaxies, the CfA2-South catalog, using statistical methods which do not rely on the assumption of homogeneity. We find that, up to ~ 20 Mpc/h, which…

Astrophysics · Physics 2009-10-31 M. Joyce , M. Montuori , F. Sylos Labini

The impact of stochastic gas motions on the metal distribution in cluster core is evaluated. Peaked abundance profiles are a characteristic feature of clusters with cool cores and abundance peaks are likely associated with the brightest…

Astrophysics · Physics 2009-11-10 P. Rebusco , E. Churazov , H. Boehringer , W. Forman

We aim at a detailed description of the kinematic properties of the old, (several Gyrs) late-type CO-absorption star population among the Galactic centre (GC) cluster stars. We applied AO-assisted, near-infrared imaging and integral-field…