相关论文: Clusters of Galaxies at z > 1
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…
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…
Using traditional morphological classifications of galaxies in 10 intermediate-redshift (z~0.5) clusters observed with WFPC-2 on the Hubble Space Telescope, we derive relations between morphology and local galaxy density similar to that…
The XMM--LSS project is detecting distant clusters of low mass, quite comparable in mass to the ones in the local universe. This allows a direct comparison of galaxy properties at different redshifts in ``similar'' clusters. We present here…
The advent of 8m-class telescopes has made galaxies at 1 < z < 4 relatively easy to detect and study. This is a brief and incomplete review of some of the recent results to emerge from surveys at these redshifts. After describing different…
We discuss the structural and morphological properties of galaxies in a z=1.62 proto-cluster using near-IR imaging data from Hubble Space Telescope Wide Field Camera 3 data of the Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey…
We derive the fraction of blue galaxies in a sample of clusters at z < 0.11 and the general field at the same redshift. The value of the blue fraction is observed to depend on the luminosity limit adopted, cluster-centric radius and, more…
We show that the rapid evolution in the fraction of blue, star-forming galaxies seen in clusters as a function of redshift (the Butcher-Oemler effect) can be explained very simply if structure formation in the universe proceeeds…
At large redshifts, a cluster or group may be too distant for the galaxies within the cluster to be detected individually. However, the light from these ``undetected'' galaxies still modulates the surface brightness of the background sky.…
(Abridged) We analyze photometry and spectroscopy of a sample of 63 clusters at 0.3<z<0.9 drawn from the Las Campanas Distant Cluster Survey to empirically constrain models of cluster galaxy evolution. Specifically, by combining data on our…
We have studied the evolution of galaxian morphologies from ground-based, good-seeing images of 9 clusters at z=0.09-0.25. The comparison of our data with those relative to higher redshift clusters (Dressler et al. 1997) allowed us to trace…
We present the ellipticity distribution and its evolution for early-type galaxies in clusters from z~0.8 to z~0, based on the WIde-field Nearby Galaxy-cluster Survey (WINGS)(0.04<z<0.07), and the ESO Distant Cluster Survey…
New ground-based and HST observations of distant clusters make it possible to trace the history of E/S0 galaxies to lookback times of ~10 $h_{50}^{-1}$ Gyr. The data strongly favor a scenario in which cluster ellipticals formed very early…
The present paper focuses on the much debated Butcher-Oemler effect: the increase with redshift of the fraction of blue galaxies in clusters. Considering a representative cluster sample made of seven group/clusters at z~0.35, we have…
We present a color analysis of the galaxy populations of candidate clusters of galaxies from the Palomar Distant Cluster Survey (Postman et al.\ 1996). The survey was conducted in two broad band filters that closely match $V$ and $I$ and…
We present multi-fiber spectroscopy and broadband imaging of early-type galaxies in five nearby rich clusters of galaxies. The main purpose was to look for ``abnormal'' spectrum galaxies (i.e., post-starburst galaxies which have strong…
We present photometric and spectroscopic measurements of the galaxy populations in clusters from the CNOC1 sample of rich, X-ray luminous clusters at $0.18 < z < 0.55$. A classical measure of the galaxy blue fraction for spectroscopically…
The complex problem of when and how galaxies formed has not until recently been susceptible of direct attack. It has been known for some time that the excessive number of blue galaxies counted at faint magnitudes implies that a considerable…
Rest frame Stromgren photometry (3500A, 4100A, 4750A and 5500A) is presented for 509 galaxies in 17 rich clusters between z=0 and z=1 as a test of color evolution. Our observations confirm a strong, rest frame, Butcher-Oemler effect where…
We review the observational evidence showing that luminous cluster elliptical galaxies are old stellar systems, undergoing mostly passive stellar evolution up to redshift $z\approx 1$, with approximate coeval epoch of formation. This…