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Two-dimensional high-resolution density field of galaxies of the Las Campanas Redshift Survey (LCRS) with a smoothing length 0.8 Mpc/h is used to extract clusters and groups of galaxies, and a low-resolution field with a smoothing length 10…

Astrophysics · Physics 2009-11-07 J. Einasto , M. Einasto , G. H"utsi , E. Saar , D. L. Tucker , E. Tago , V. M"uller , P. Hein"am"aki , S. S. Allam

We present an improved determination of the total mass distribution of three CLASH/HFF massive clusters, MACS J1206.2-0847 (z=0.44), MACS J0416.1-2403 (z=0.40), Abell S1063 (z=0.35). We specifically reconstruct the sub-halo mass component…

We present distribution functions and spatial correlations of the shapes of dark matter halos derived from Hubble Volume simulations of a LambdaCDM universe. We measure both position and velocity shapes within spheres encompassing mean…

Astrophysics · Physics 2008-11-26 S. F. Kasun , A. E. Evrard

We show that the evolution of the number density of rich clusters of galaxies breaks the degeneracy between Omega (the mass density ratio of the universe) and sigma_{8} (the normalization of the power spectrum), sigma_{8}Omega^{0.5} \simeq…

Astrophysics · Physics 2009-10-30 Neta A. Bahcall , Xiaohui Fan , Renyue Cen

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…

Astrophysics · Physics 2019-08-19 Renato A. Dupke , Nestor Mirabal , Joel N. Bregman , August E. Evrard

The caustic technique for measuring mass profiles of galaxy clusters relies on the assumption of spherical symmetry. When applied to aspherical galaxy clusters, the method yields mass estimates affected by the cluster orientation. Here we…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-19 Jacob Svensmark , Radoslaw Wojtak , Steen H. Hansen

We present a numerical study of the relation between the cosmic peculiar velocity field and the gravitational acceleration field. We show that on mildly non-linear scales (4-10 Mpc Gaussian smoothing), the distribution of the Cartesian…

I present recent progress in theoretical modelling of cosmological density--velocity relations in the weakly nonlinear regime. The relations are local, based on rigorous perturbation theory and include the effects of smoothing of the…

Astrophysics · Physics 2007-05-23 Michal Chodorowski

We present a dynamical analysis of the galaxy cluster Abell 970 based on a new set of radial velocities measured at ESO, Pic du Midi and Haute-Provence observatories. Our analysis indicates that this cluster has a substructure and is out of…

Astrophysics · Physics 2009-10-31 L. Sodre , D. Proust , H. V. Capelato , G. B. Lima Neto , H. Cuevas , H. Quintana , P. Fouque

Velocity fields in the cosmic web are fundamental to structure formation but remain difficult to observe directly beyond the linear regime. Here we present observational evidence that galaxy filaments connecting pairs of galaxy clusters…

Cosmology and Nongalactic Astrophysics · Physics 2026-01-27 Ji Yao , Huanyuan Shan , Pengjie Zhang , Xiaohu Yang , Jiale Zhou , Jiaxin Han , Peng Wang

We present an efficient and robust approach for extracting clusters of galaxies from weak lensing survey data and measuring their properties. We use simple, physically-motivated cluster models appropriate for such sparse, noisy data, and…

Astrophysics · Physics 2008-10-07 F. Feroz , P. J. Marshall , M. P. Hobson

The peculiar velocity of a mass tracer is on average aligned with the dipole modulation of the surrounding mass density field. We present a first measurement of the correlation between radial peculiar velocities of objects in the…

Cosmology and Nongalactic Astrophysics · Physics 2017-06-28 Adi Nusser

We investigate the supercluster shape properties of the all-sky observed (Abell/ACO) and simulated (Virgo data) cluster catalogues using an approach based on differential geometry. We reliably identify rich superclusters by applying…

Astrophysics · Physics 2010-03-19 V. Kolokotronis , S. Basilakos , M. Plionis

Context: The shape of the mass density profiles of cosmological halos informs us of the nature of DM and DM-baryons interactions. Previous estimates of the inner slope of the mass density profiles of clusters of galaxies are in opposition…

Cosmology and Nongalactic Astrophysics · Physics 2020-05-13 B. Sartoris , A. Biviano , P. Rosati , A. Mercurio , C. Grillo , S. Ettori , M. Nonino , K. Umetsu , P. Bergamini , G. B. Caminha , M. Girardi

The properties of nearby galaxy clusters limit the range of cosmological parameters consistent with our universe. We describe the limits which arise from studies of the intracluster medium (ICM) mass fraction fICM and consideration of the…

Astrophysics · Physics 2016-11-03 Joseph J. Mohr , Zoltan Haiman , Gilbert P. Holder

The CNOC redshift survey of galaxy clusters measures Omega_M from Omega_e(z)= M/L x j/\rho_c which can be applied on a cluster-by-cluster basis. The mass-to-light ratios, M/L, are estimated from rich galaxy clusters, corrected to the field…

A direct approach to studying the galaxy-halo connection is to analyze groups and clusters of galaxies that trace the underlying dark matter halos, emphasizing the importance of identifying galaxy clusters and their associated brightest…

Cosmology and Nongalactic Astrophysics · Physics 2025-01-22 Hai-Xia Ma , Tsutomu T. Takeuchi , Suchetha Cooray , Yongda Zhu

We present new redshift measurements for 55 galaxies in the vicinity of the rich galaxy cluster Abell 665. When combined with results from the literature, we have good velocity measurements for a sample of 77 confirmed cluster members from…

Astrophysics · Physics 2009-10-31 Percy L. Gomez , John P. Hughes , Mark Birkinshaw

There are only two methods for estimating the mass distribution in the outer regions of galaxy clusters, where virial equilibrium does not hold: weak gravitational lensing and identification of caustics in redshift space. For the first…

Astrophysics · Physics 2009-11-13 Antonaldo Diaferio , Margaret J. Geller , Kenneth J. Rines

Much current interest in cosmology has revolved around the peculiar velocity field of galaxies. Many methods have been proposed to derive this, probably the most prominent being POTENT (Dekel et al. 1990). However, this is prone to many…

Astrophysics · Physics 2007-05-23 A. Newsam , J. F. L. Simmons , M. A. Hendry