Related papers: Low redshift quasars in the SDSS Stripe 82. The lo…
We report the discovery of a quiescent galaxy at $z=2.34$ with a stellar mass of only $M_\star = 9.5^{+1.8}_{-1.2} \times 10^{8} \mathrm{M}_\odot$, based on deep JWST/NIRSpec spectroscopy. This is the least massive quiescent galaxy found so…
Massive quiescent galaxies (QGs) at high redshifts are likely progenitors of massive elliptical galaxies in the local Universe. Recent observations, such as the discovery of QGs in overdensity (galaxy groups and proto-clusters) at high…
We examine the clustering of galaxies around a sample of 20 luminous low redshift (z<0.30) quasars observed with the Wide Field Camera-2 on the Hubble Space Telescope. The HST resolution makes possible galaxy identification brighter than…
We investigate the environment of infrared luminous galaxies (L$_{IR}$[8-1000 $\mu $m$] >10^{11}$L$_{\sun}$). We focus on the redshift range 0.7 $\leq$ z $\leq$ 1, where these galaxies dominate the star formation activity and play a…
We present simulations of quasar colors, magnitudes, and numbers at redshifts 5<z<10 based on our discovery of ten new high-redshift quasars and the cloning of lower redshift Sloan Digital Sky Survey (SDSS) quasars. The ten quasars have…
We investigate the relationship between quasars and close companion galaxies using photometry and spectroscopy from the large data set of the SDSS DR16 survey. From the SDSS-QSO catalog of quasars, we selected objects with 0.1 < z < 0.35…
We calculate in detail the expected properties of low redshift DLA systems under the assumption that they arise in the gaseous disks of galaxies like those in the z=0 population. A sample of 355 nearby galaxies is analysed, for which high…
The SDSS-III BOSS Quasar survey will attempt to observe z>2.15 quasars at a density of at least 15 per square degree to yield the first measurement of the Baryon Acoustic Oscillations in the Ly-alpha forest. To help reaching this goal, we…
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 measurements of the quasar two-point correlation function, \xi_{Q}, over the redshift range z=0.3-2.2 based upon data from the SDSS. Using a homogeneous sample of 30,239 quasars with spectroscopic redshifts from the DR5 Quasar…
High-$z$ quasars are believed to reside in massive dark matter haloes (DMHs), suggesting that they reside in galaxy overdense regions. However, previous observations have shown a range of environments around them. These fields have been…
The size-mass galaxy distribution is a key diagnostic for galaxy evolution. Massive compact galaxies are potential surviving relics of a high-redshift phase of star formation. Some of these could be nearly unresolved in SDSS imaging and…
We compare environmental effects in two analogous samples of galaxies, one from the Sloan Digital Sky Survey (SDSS) and the other from a semi-analytic model (SAM) based on the Millennium Simulation (MS), to test to what extent current SAMs…
The dynamical properties of six SDSS quasar pairs at z < 0.8 are investigated. The pairs have proper transverse separation < 500 kpc, and velocity difference along the line of sight < 500 km/s. If they are bound systems their dynamical mass…
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 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…
We use optical and near-IR imaging to examine the properties of the significant excess population of K>=19 galaxies found in the fields of 31 z=1-2 radio-loud quasars by Hall, Green & Cohen (1998). The excess occurs on two spatial scales: a…
Measuring the environments of massive galaxies at high redshift is crucial to understanding galaxy evolution and the conditions that gave rise to the distribution of matter we see in the Universe today. While high-$z$ radio galaxies…
Deep optical images have been gathered for a nearly complete sample of radio galaxies from the Revised 3rd Cambridge (3CR) Catalog in the redshift range 0.15 < z < 0.65. Total and nuclear magnitudes and colors have been extracted. The…
We investigate the evolution of compact galaxy number density over the redshift range $0.2<z<0.8$. Our sample consists of galaxies with secure spectroscopic redshifts observed in the COSMOS field. With the large uncertainties, the compact…