Related papers: The most distant compact groups
We found a new, very compact group of galaxies characterized by a median projected separation between galaxies of 5.2/h kpc and a very low velocity dispersion. All the observed member galaxies show emission line spectra and a disturbed…
Compact groups (CGs) of galaxies -- relatively poor groups of galaxies in which the typical separations between members is of the order of a galaxy diameter -- offer an exceptional laboratory for the study of dense galaxian environments…
Although Compact Groups of galaxies (CGs) have been envisioned as isolated extremely dense structures in the Universe, it is accepted today that many of them could be not as isolated as thought. In this work, we study Hickson-like CGs…
We consider a sample of about 50 distant galaxy clusters at z>0.15 (<z> about 0.3), each cluster having at least 10 galaxies with available redshift in the literature. We select member galaxies, analyze the velocity dispersion profiles, and…
Candidate clusters of galaxies drawn from the sample identified from the moderately deep I-band data of the ESO Imaging Survey (EIS), have been used for follow-up optical/infrared imaging and spectroscopic observations. The observations…
We present a study on the physical properties of compact star-forming galaxies (cSFGs) with $M_{*}\geq10^{10}M_{\odot}$ and $2\leq z\leq3$ in the COSMOS and GOODS-S fields. We find that massive cSFGs have a comoving number density of…
Quiescent massive galaxies at z~2 are thought to be the progenitors of present-day massive ellipticals. Observations revealed them to be extraordinarily compact. The determination of stellar ages, star formation rates and dust properties…
The slow evolution of the M/L ratios, colors, and line strengths of cluster early-type galaxies to z=1 suggests that their stars were formed at very high redshift. At the same time, morphological studies of distant clusters indicate…
Cluster ellipticals are often thought to be among the oldest galaxies in the universe, with the bulk of their stellar mass formed at early cosmic epochs. I review recent observations of color evolution in early-type cluster galaxies at high…
We discuss the properties of galaxies around the radio galaxy 3C 324 at z=1.2 based on BVRIK' multi-band imaging data. We have applied a photometric-redshift technique to objects in the 3C 324 field, and identified 35 objects as plausible…
We present HST images of star-forming galaxies at redshifts z>3. These galaxies have been color selected for having a Lyman discontinuity in the otherwise flat (in f_\nu units) UV spectra of unreddened star formation. The spectroscopic…
We present a combined study of the colour-magnitude relation, colour distribution and luminosity function of a sample of 24 clusters at redshifts 0.3<z<1. The sample is largely composed of X-ray selected/detected clusters. Most of the…
We have undertaken a multiwavelength project to study the relatively unknown properties of groups and poor clusters of galaxies at intermediate redshifts. In this paper, we describe the XMM-Newton observations of six X-ray selected groups…
From several searches of the area common to the Sloan Digital Sky Survey and the United Kingdom Infrared Telescope Infrared Deep Sky Survey, we have selected 22 luminous galaxies between $z \sim$ 0.4 and $z \sim$ 0.9 that have colors and…
We investigate the differences in the stellar population properties, the structure, and the environment between massive compact star-forming galaxies (cSFGs) with or without active galactic nucleus (AGN) at $2<z<3$ in the five…
We report on our search for distant clusters of galaxies based on optical and X-ray follow up observations of X-ray candidates from the SHARC survey. Based on the assumption that the absence of bright optical or radio counterparts to…
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…
In this paper, we are exploring the properties of old, metal-poor globular clusters in galaxies. We investigate whether their properties are related to the properties of their host galaxies, and whether we can constrain their formation. The…
In the local Universe, galaxy properties show a strong dependence on environment. In cluster cores, early type galaxies dominate, whereas star-forming galaxies are more and more common in the outskirts. At higher redshifts and in somewhat…
(Abridged) We present new optical and near-infrared imaging for a sample of 98 spectroscopically-selected galaxy groups at 0.25<z<0.55. We measure accurate colours for group members and the surrounding field population, statistically…