Related papers: A QSO in a Cluster at z=2.4

It is shown that there are at least 21 QSOs within 1 degree of the nearby active spiral galaxy NGC3079. Many of them are bright (mag<18) so that the surface density of those closer than 15 arc minutes to the galaxy centre is close to 100…

An angular correlation of low significance (2 sigma) is observed between 0.3 < z < 0.5 QSOs and V < 23 galaxies. Overall, the cross-correlation function between 82 intermediate-redshift (0.3 < z < 0.7), X-ray selected QSOs and V < 24…

We present an investigation of the environment (\approx 600 kpc radius) of a pair of luminous z=4.25 quasars, SDSS J1439-0034 A,B, separated by 33''. An analysis of high-quality Subaru spectra of the quasars suggests that this configuration…

We present an analysis of the environment of six QSO triplets at 1 $\lesssim$ z $\lesssim$ 1.5 by analyzing multiband (r,i,z, or g,r,i) images obtained with Megacam at the CFHT telescope, aiming to investigate whether they are associated or…

We report on a wide-area (48' x 9') imaging survey of faint galaxies in R and I bands toward the 1338+27 field where an unusual concentration of five QSOs at z\sim1.1, embedded in a larger-scale clustering of 23 QSOs, is known to exist.…

We report on the spectroscopic confirmation of a huge cosmic structure around the CL0016 cluster at z=0.55. We made wide-field imaging observations of the surrounding regions of the cluster and identified more than 30 concentrations of red…

We have analyzed the clustering of C IV absorption line systems in an extensive new catalog of heavy element QSO absorbers. The catalog permits exploration of clustering over a large range in both scale (from about 1 to over 300 Mpc) and…

We present deep I, J_s, K_s imaging and optical spectroscopy of the newly discovered Red-Sequence Cluster Survey cluster RCS043938-2904.9. This cluster, drawn from an extensive preliminary list, was selected for detailed study on the basis…

A recently discovered quadruply-imaged QSO, SDSS J1004+4112 (Inada et al. 2003; Oguri et al. 2004) in the core of a $z=0.68$ galaxy cluster has an unprecedented image separation of ~13''. This lens gives us a unique opportunity to study the…

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…

Globular clusters will be present at high redshifts, near the very beginning of the galaxy formation process. Stellar evolution ensures that they will be much more luminous than today. We show that the redshift distribution at nano-Jansky…

We have discovered two new high redshift (z=2.38) galaxies, near the previously known z=2.38 galaxy 2139-4434 B1 (Francis et al. 1996). All three galaxies are strong Ly-alpha emitters, and have much redder continuum colors (I-K about 5)…

We present a multi-wavelength study of RX J0848+4456, a cluster of galaxies discovered through X-ray emission in the ROSAT Deep Cluster Survey. Our observations consist of WFPC2 imaging, optical spectra, and X-ray data collected with the…

We present strong evidence for the existence of a supercluster at a redshift of z=0.54 in the direction of Selected Area 68. From the distribution of galaxies with spectroscopic redshifts we find that there is a large over-density of…

Two-dimensional surface photometry derived from Hubble Space Telescope imaging is presented for a sample of 225 early-type galaxies (assumed to be cluster members) in the fields of 9 clusters at redshifts $0.17 < z < 1.21$. The 94 luminous…

In this thesis, I present an investigation into the environments of quasars with respect to galaxy clusters, and environment evolution with redshift and luminosity. The orientation of the quasar with respect to the major axis of the closest…

Large-scale surveys over the last years have revealed about 300 QSOs at redshift above 6. Follow-up observations identified surprising properties, such as the very high black hole (BH) masses, spatial correlations with surrounding cold gas…

We have carried out an investigation of the galaxy environments of low redshift ($z<0.3$) QSOs by cross-correlating the positions on the sky of X-ray-selected QSOs/AGN identified in the {\it Einstein} Medium Sensitivity Survey (EMSS) with…

Distant clusters of galaxies provide a powerful method to study the formation and evolution of galaxies, and large scale structure of the Universe. However, the number of known clusters at high redshift (z> 0.5) is still very reduced. As a…

New JWST/NIRCam wide-field slitless spectroscopy provides redshifts for four z>8 galaxies located behind the lensing cluster MACS J0416.1-2403. Two of them, "Y1" and "JD", have previously reported spectroscopic redshifts based on ALMA…