Related papers: A large-scale galaxy structure at z = 2.02 associa…

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…

We report the discovery of a galaxy overdensity at z=1.11 associated with the z=1.110 high-redshift radio galaxy MG0442+0202. The group, CL0442+0202, was found in a near-infrared survey of z>1 radio galaxies undertaken to identify…

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…

PKS 1138-262 is a massive radio galaxy at z = 2.16 surrounded by overdensities of Lya emitters, Ha emitters, EROs and X-ray emitters. Numerous lines of evidence exist that it is located in a forming cluster. We report on Keck spectroscopy…

VLT spectroscopic observations of Ly alpha--excess objects in the field of the clumpy radio galaxy 1138-262 at z=2.16 have led to the discovery of 14 galaxies and one QSO at approximately the same distance as the radio galaxy. All galaxies…

Using HST slitless grism data, we report the spectroscopic confirmation of two distant structures at $z \sim 2$ associated with powerful high-redshift radio-loud AGN. These rich structures, likely (forming) clusters, are among the most…

We report here the spectroscopic identification of galaxies in the neighborhood of the radio-galaxy MRC0316-257, at a redshift $z\sim3.14$. Candidate cluster galaxies were selected from deep V and I images combined with narrow band imaging…

We present spectroscopic follow-up of an overdensity of galaxies photometrically selected to be at 1.4<z<2.5 found in the vicinity of the radio galaxy 7C1756+6520 at z=1.4156. Using the DEIMOS optical multi-object spectrograph on the Keck 2…

We present results from a Chandra X-ray Observatory study of the field X-ray source population in the vicinity of the radio galaxy MRC 1138-262. Many serendipitous X-ray sources are detected in an area of 8'x8' around the radio source and…

We present deep observations taken with the HST Advanced Camera for Surveys of the central massive galaxy in a forming cluster at z=2.2. The galaxy hosting the powerful radio source MRC 1138-262 is associated with one of the most extensive…

We present APEX LABOCA 870 micron observations of the field around the high-redshift radio galaxy MRC1138-262 at z=2.16. We detect 16 submillimeter galaxies in this ~140 square arcmin bolometer map with flux densities in the range 3-11 mJy.…

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…

Radio galaxies are uniquely useful as probes of large-scale structure as their uniform identification with giant elliptical galaxies out to high redshift means that the evolution of their bias factor can be predicted. As the initial stage…

We study the stellar mass assembly of the Spiderweb Galaxy (MRC 1138-262), a massive z = 2.2 radio galaxy in a protocluster and the probable progenitor of a brightest cluster galaxy. Nearby protocluster galaxies are identified and their…

Radio galaxies are excellent at tracing large-scale structure due to their high bias. We present new results from the TONS08 radio galaxy redshift survey. We find unequivocal evidence for a huge (at least 80 x 80 x 100 Mpc^3)…

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 have discovered a previously unreported poor cluster of galaxies (RGZ-CL J0823.2+0333) through an unusual giant wide-angle tail radio galaxy found in the Radio Galaxy Zoo project. We obtained a spectroscopic redshift of $z=0.0897$ for…

We have recently discovered a forming cluster around the radio galaxy MRC 1138-262 at redshift 2.2. Besides the population of Ly alpha emitting galaxies that have been confirmed spectroscopically, we have detected many candidate H alpha…

We present results from a narrow-band survey of the field around the high redshift radio galaxy MRC 2104-242. We have selected Halpha emitters in a 7sq.arcmin field and compared the measured number density with that of a field sample at…

High-redshift radio galaxies can provide insights into the structure formation and galaxy evolution at earlier cosmological epochs. TGSSJ1530+1049 was selected as a candidate high-redshift radio galaxy. Subsequent observations with the…