相关论文: Passive galaxies as tracers of cluster environment…
High-redshift galaxy clusters, unlike local counterparts, show diverse star formation activities. However, it is still unclear what keeps some of the high-redshift clusters active in star formation. To address this issue, we performed a…
We have discovered a highly significant over-density of galaxies at z=2.300+/-0.015 in the course of a redshift survey designed to select star-forming galaxies in the redshift range z=2.3+/-0.4 in the field of the bright z=2.72 QSO…
We present three candidate clusters of galaxies at redshifts most likely between 1.7 and 2.0, which corresponds to a fundamentally unexplored epoch of clusters evolution. The candidates were found by studying the environment around our…
Galaxy clusters are crucial to understanding role of the environment in galaxy evolution. However, due to their rarity, only a limited number of clusters have been identified at $z\gtrsim2$. In this paper, we report a discovery of seven…
We report a promising candidate for a distant supercluster at z $\sim 1.1$ in the Dark Energy Survey Science Verification data. We examine smoothed semi-3D galaxy density maps in various photo-z slices. Among several overdense regions, in…
We present a study of galaxy populations in the central region of the IRAC-selected, X-ray detected galaxy cluster Cl J1449+0856 at z=2. Based on a sample of spectroscopic and photometric cluster members, we investigate stellar populations…
From a search of a ~ 2400 square degree region covered by both the SDSS and UKIDSS databases, we have attempted to identify galaxies at z ~ 0.5 that are consistent with their being essentially unmodified examples of the luminous passive…
As the densest galaxy environments in the universe, clusters are vital to our understanding of the role that environment plays in galaxy formation and evolution. Unfortunately, the evolution of high-redshift cluster galaxies is poorly…
Massive galaxy clusters are now found as early as 3 billion years after the Big Bang, containing stars that formed at even earlier epochs. The high-redshift progenitors of these galaxy clusters, termed 'protoclusters', are identified in…
The importance of studying old elliptical galaxies at redshift z ~ 1.5 is reviewed, considering both what can be learned by extending studies of the evolution of cluster galaxy scaling relations to earlier cosmic epochs, and the age-dating…
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…
Galaxy environment is frequently discussed, but inconsistently defined. It is especially difficult to measure at high redshift where only photometric redshifts are available. With a focus on early forming proto-clusters, we use a…
We use the UKIDSS Ultra-Deep Survey, the deepest degree-scale near-infrared survey to date, to investigate the clustering of star-forming and passive galaxies to z ~ 3.5. Our new measurements include the first determination of the…
To demonstrate the feasibility of studying the epoch of massive galaxy cluster formation in a more systematic manner using current and future galaxy surveys, we report the discovery of a large sample of proto-cluster candidates in the 1.62…
Clusters of galaxies at z>1 are expected to be increasingly active sites of star formation. To test this, an 850um survey was undertaken of eight high-redshift clusters at z=1.6-2.0 using SCUBA-2 on the James Clerk Maxwell Telescope.…
We report the first results from the Z-FOURGE survey: the discovery of a candidate galaxy cluster at z = 2.2 consisting of two compact overdensities with red galaxies detected at >20{\sigma} above the mean surface density. The discovery was…
We present an analysis of stellar populations in passive galaxies in seven massive X-ray clusters at z=0.19-0.89. Based on absorption line strengths measured from our high signal-to-noise spectra, the data support primarily passive…
There are at least three reasons for being interested in galaxies at high redshifts that formed most of their stars quite quickly early in the history of the Universe: (1) the ages of their stellar populations can potentially place…
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…
We search for passive galaxies at $z>3$ in the GOODS-South field, using different techniques based on photometric data, and paying attention to develop methods that are sensitive to objects that have become passive shortly before the epoch…