Related papers: JKCS041: a Coma cluster progenitor at z=1.803
We present a study of the galaxy population in the cluster RXJ0848+4453 at z=1.27, using deep HST NICMOS and WFPC2 images. We morphologically classify all galaxies to K_s=20.6 that are covered by the HST imaging, and determine photometric…
We use Hectospec mounted on the 6.5-meter MMT to carry out a redshift survey of red ($r-i>0.2$, $g-r>0.8$, $r<21.3$) galaxies in the COSMOS field to measure the environments of massive compact quiescent galaxies at intermediate redshift.…
Protoclusters of galaxies have been found in the last quarter century. However, most of them have been found through the overdensity of star-forming galaxies, and there had been no known structures identified by multiple spectroscopically…
We present new Chandra observations of a high redshift (z~1) galaxy cluster discovered in the Red-Sequence Cluster Survey (RCS): RCS043938-2904.7. X-ray luminosity measurements and mass estimates are consistent with L_X-T_X and M_delta-T_X…
XMMU J1229+0151 is a rich galaxy cluster with redshift z=0.975, that was serendipitously detected in X-rays within the scope of the XMM-Newton Distant Cluster Project. HST/ACS observations in the i775 and z850 passbands, as well as…
We present low-resolution near-infrared stacked spectra from the 3D-HST survey up to $z=2.0$ and fit them with commonly used stellar population synthesis models: BC03 (Bruzual & Charlot, 2003), FSPS10 (Flexible Stellar Population Synthesis,…
The Coma cluster is the ideal place to study galaxy structure as a function of environmental density in order to constrain theories of galaxy formation and evolution. Here we present the spectroscopy of 35 early type Coma galaxies, which…
We present an extensive photometric and spectroscopic study of two high-redshift clusters of galaxies based on data obtained from the Keck 10m telescopes and the Hubble Space Telescope. The clusters CL0023+0423 (z=0.84) and CL1604+4304…
Clusters and their progenitors (protoclusters) at z = 2-4, the peak epoch of star formation, are ideal laboratories to study the formation process of both the clusters themselves and their member galaxies. However, a complete census of…
As a continuation of our study of the faint galaxy luminosity function in the Coma cluster of galaxies, we report here on the first spectroscopic observations of very faint galaxies (R $\le$ 21.5) in the direction of the core of this…
The origin of the correlations between mass, morphology, quenched fraction, and formation history in galaxies is difficult to define, primarily due to the uncertainties in galaxy star-formation histories. Star-formation histories are better…
We present an analysis of the galaxy stellar mass function (SMF) of 14 known protoclusters between $2.0 < z < 2.5$ in the COSMOS field, down to a mass limit of $10^{9.5}$ M$_{\odot}$. We use existing photometric redshifts with a statistical…
Recent simulations and observations of massive galaxy cluster evolution predict that the majority of stellar mass build up happens within cluster members by $z=2$, before cluster virialization. Protoclusters rich with dusty, star-forming…
The Chandra X-ray Observatory was used to obtain a 190 ks image of three high redshift galaxy clusters in one observation. The results of our analysis of these data are reported for the two z > 1 clusters in this Lynx field, including the…
X-ray luminous clusters of galaxies at z~1 are emerging as major cosmological probes and are fundamental tools to study the cosmic large-scale structure and environmental effects of galaxy evolution at large look-back times. We present…
A photometric redshift analysis of galaxies in the field of the wide-separation gravitational lens MG2016+112 reveals a population of 69 galaxies with photometric redshifts consistent with being in a cluster at the redshift of the giant…
Using data from JWST, we analyze the compact sources ("sparkles") located around a remarkable $z_{\rm spec}=1.378$ galaxy (the "Sparkler") that is strongly gravitationally lensed by the $z=0.39$ galaxy cluster SMACS J0723.3-7327. Several of…
The redshift of $z\sim1.5$ is the transition epoch of protoclusters (PCs) from the star-forming phase into the quenching phase, and hence an appropriate era to investigate the build up of the quenched population. We define a `core' as the…
We study the growth of the red sequence through the number density and structural evolution of a sample of young and old quiescent galaxies at 0<z<2. The galaxies are selected from the NEWFIRM Medium-Band Survey (NMBS) in the Cosmic…
We have identified a clustering of red galaxies from deep optical/IR images obtained as part of the Institute for Astronomy Deep Survey. Photometric spectral-energy distributions indicate that most of these galaxies comprise nearly pure old…