Related papers: Proto-Clusters with Evolved Populations around Rad…
We study the environments of 6 radio galaxies at 2.2 < z < 2.6 using wide-field near-infrared images. We use colour cuts to identify galaxies in this redshift range, and find that three of the radio galaxies are surrounded by significant…
We explore the evolved galaxy population in the proto-clusters around four high-z radio galaxies at 2<~z<~3 based on wide-field near-infrared imaging. Three of the four fields are known proto-clusters as demonstrated by overdensities of…
[Abridged] We present the results of a large program conducted with the Very Large Telescope and Keck telescope to search for forming clusters of galaxies near powerful radio galaxies at 2.0 < z < 5.2. We obtained narrow- and broad-band…
We explore the environments of two radio galaxies at z~1.5, 7C1751+6809 and 7C1756+6520, using deep optical and near-infrared imaging. Our data cover 15'x15' fields around the radio galaxies. We develop and apply BzK color criteria to…
The importance of studying old elliptical galaxies at redshift z ~ 1.5 is reviewed, considering both what can be learned by extending studies of the evolution of cluster galaxy scaling relations to earlier cosmic epochs, and the age-dating…
We present a study of protoclusters associated with high redshift radio galaxies. We imaged MRC1017-220 (z=1.77) and MRC0156-252 (z=2.02) using the near-infrared wide-field (7.5'x7.5') imager VLT/HAWK-I in the Y, H and Ks bands. We present…
An analysis of the cluster environments around distant radio galaxies is presented, in particular the results from new NTT deep optical-IR imaging of the fields of radio sources at z ~ 1.6. A net overdensity of K-band galaxies is found,…
High redshift radio galaxies are amongst the most massive galaxies in the early Universe and have properties expected from central galaxies in forming clusters. We are carrying out an observational programme on the VLT to find and study…
This paper presents the first results of a far-infrared search for protocluster-associated galaxy overdensities using the SPIRE instrument on-board the {\it Herschel} Space Observatory. Large ($\sim$400 arcmin$^{2}$) fields surrounding 26…
We present near-infrared observations of the environments around three radio-loud sources (MG1 J0442+0202, 3C 068.2, and MS 1426.9+1052) at redshifts z=1.10,1.57, and 1.83 (respectively), that are surrounded by near-infrared galaxy…
Taking advantage of the impressive sensitivity of Spitzer to detect massive galaxies at high redshift, we study the mid-infrared environments of powerful, high-redshift radio galaxies at 1.2<z<3. Galaxy cluster member candidates were…
We have discovered a highly significant over-density of galaxies at z=2.300+/-0.015 in the course of a redshift survey designed to select star-forming galaxies in the redshift range z=2.3+/-0.4 in the field of the bright z=2.72 QSO…
We examine the redshift evolution of density environments around 2,163 radio galaxies with the stellar masses of $\sim10^{9}-10^{12} M_\odot$ between redshifts of $z=0.3-1.4$, based on the Hyper Suprime-Cam Subaru Strategic Program…
To properly understand the evolution of high-redshift galaxy clusters, both passive and star-forming galaxies have to be considered. Here we study the clustering environment of 21 radio galaxies and quasars at 1<z<2.5 from the third…
The clustering properties of clusters, galaxies and AGN as a function of redshift are briefly discussed. It appears that extremely red objects at z ~ 1, and objects with J-K > 1.7 and photometric redshifts 2 < z_phot < 4 are highly…
Radio galaxies are among the most massive galaxies in the high redshift universe and are known to often lie in protocluster environments. We have studied the fields of seven z = 2.2 radio galaxies with HAWK-I narrow-band and broad-band…
We present a protocluster search covering $z\sim3$ to $z\sim5$ based on the combination of the Hyper SuprimeCam Subaru Strategic Programme and the CFHT Large Area $U$-band Deep Survey. We identify about 30 protocluster candidates per unit…
I discuss the properties of a population of candidate cluster galaxies recently identified in the fields of radio-loud quasars at z=1--2. The magnitude, spatial, and color distributions of the excess galaxies in these fields are consistent…
We present a panoramic narrow-band study of H-alpha emitters in the field of the z=2.16 proto-cluster around PKS1138-262 using MOIRCS on the Subaru Telescope. We find 83 H-alpha emitters down to a SFR(Ha)~10Msun/yr across a ~7'x7' region…
We present three candidate clusters of galaxies at redshifts most likely between 1.7 and 2.0, which corresponds to a fundamentally unexplored epoch of clusters evolution. The candidates were found by studying the environment around our…