Related papers: The Medium Redshift Clusters CL0017-20 and CL0500-…

We report the discovery of a remarkable concentration of massive galaxies with extended X-ray emission at $z_{spec} = 2.506$, which contains 11 massive ($M_{*} \gtrsim 10^{11} M_{\odot}$) galaxies in the central 80kpc region (11.6$\sigma$…

We reanalyze the strong lens modeling of the cluster of galaxies MS2137-23 using a new data set obtained with the ESO VLT. We found the photometric redshifts of the two main arc systems are both at z=1.6. After subtraction of the central cD…

We compare the highly clustered populations of very high redshift galaxies with proto-clusters identified numerically in a standard $\Lambda$CDM universe ($\Omega_0=0.3, \lambda_0=0.7$) simulation. We evolve 256^3 dark matter particles in a…

We previously reported a significant clustering of red galaxies (R-K=3.5--6) around the radio-loud quasar B2 1335+28 at z=1.086. In this paper, we establish the existence of a rich cluster at the quasar redshift, and study the properties of…

We report the discovery of a galaxy cluster serendipitously detected as an extended X-ray source in an offset observation of the group NGC 5044. The cluster redshift, z=0.281, determined from the optical spectrum of the brightest cluster…

We study the properties of the fossil cluster RX J1416.4+2315 through g' and i'-band imaging and spectroscopy of 25 member galaxies. The system is at a mean redshift of 0.137 and has a velocity dispersion of 584 km s^-1. Superimposed onto…

Ten galaxy clusters, with redshift ranging from 0.2 to 1, have been observed with the ISO camera in the two bands LW2 and LW3 (centered respectively at 6.75 and 15 microns). We present a first analysis for three of these clusters at…

Massive galaxy clusters are interesting astrophysical and cosmological study objects, but are relatively rare. In the redshift range z = 0.25 to 0.5 which is, for example, a favourable region for gravitational lensing studies, about 100…

We derive an accurate mass distribution of the rich galaxy cluster Cl0024+1654 (z=0.395) based on deep Subaru BR_{c}z' imaging and our recent comprehensive strong lensing analysis of HST/ACS/NIC3 observations. We obtain the weak lensing…

We present new optical data on the cluster AX J2019+1127 identified by the X-ray satellite ASCA at z\sim 1 (Hattori et al. 1997). The data suggest the presence of a high-redshift cluster of galaxies responsible for the large separation…

We have identified 335 galaxy cluster and group candidates, 106 of which are at z > 1, using a 4.5 um selected sample of objects from a 7.25 deg^2 region in the Spitzer Infrared Array Camera (IRAC) Shallow Survey. Clusters were identified…

We present a VLT/MUSE survey of lensed high-redshift galaxies behind the z=0.77 cluster RCS0224-0002. We study the detailed internal properties of a highly magnified ({\mu}~29) z=4.88 galaxy seen through the cluster. We detect wide-spread…

We explore the near-infrared (NIR) $K$-band properties of galaxies within 93 galaxy clusters and groups using data from the 2MASS. We use X-ray properties of these clusters to pinpoint cluster centers and estimate cluster masses. By…

We have obtained K-band Multi-Object Spectrograph (KMOS) near-IR spectroscopy for 14 red supergiant stars (RSGs) in the young massive star cluster NGC 2100 in the Large Magellanic Cloud (LMC). Stellar parameters including metallicity are…

We present a sample of 47 spectroscopically confirmed members of RX J1347-1145, the most luminous X-ray cluster of galaxies discovered to date. With two exceptions, all the galaxies in this sample have red B-R colors and red spectral…

We use the spherical collapse model to demonstrate that the observable average density of virialized clusters depends on the properties of dark energy along with the properties of gravity on cluster scales and can therefore be used as a…

The clustering properties of faint K<24 galaxies are measured in ultradeep J, H and K near-IR images of the Hubble Deep Field South (HDF-S), obtained with ISAAC at the VLT. A relatively large clustering amplitude is found up to K=24, at a…

We present an optical analysis of a sample of 11 clusters built from the EXCPRES sample of X-ray selected clusters at intermediate redshift (z ~ 0.5). With a careful selection of the background galaxies we provide the mass maps…

We analyzed the spatial distribution of 28500 photometrically selected galaxies with AB magnitude 23.5<R<25.5 and redshift 1.4<z<3.5 in 21 fields with a total area of 0.81 square degrees. The galaxies were divided into three subsamples,…

We analyse the cluster color-magnitude relation (CMR) for early-type galaxies in two of the richer clusters in the z ~ 0.9 supercluster system to derive average ages and formation redshifts for the early-type galaxy population. Both…