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We present new spectroscopic data in the field of five high-redshift (z>=0.6) candidate galaxy clusters, drawn from the EIS Cluster Candidate Catalog. A total of 327 spectra were obtained using FORS1 at the VLT, out of which 266 are…

Astrophysics · Physics 2009-11-11 L. F. Olsen , E. Zucca , S. Bardelli , C. Benoist , L. da Costa , H. E. Jørgensen , A. Biviano , M. Ramella

The combination of X-ray and SZ observations can potentially improve the cluster detection efficiency when compared to using only one of these probes, since both probe the same medium: the hot ionized gas of the intra-cluster medium. We…

Cosmology and Nongalactic Astrophysics · Physics 2018-06-20 Paula Tarrío , Jean-Baptiste Melin , Monique Arnaud

We use giga-particle N-body simulations to study galaxy cluster populations in Hubble Volumes of LCDM (Omega_m=0.3, Omega_Lambda=0.7) and tCDM (Omega_m=1) world models. Mapping past light-cones of locations in the computational space, we…

Current catalogues of open clusters are rather heterogeneous and incomplete lists of clusters than true catalogues. Before there has been no attempts of automatic search for open clusters in huge photometric catalogues using homogeneous…

Astrophysics · Physics 2007-05-23 Ivan Zolotukhin , Sergey Koposov , Elena Glushkova

We outline a simple procedure designed for \emph{automatically} finding sets of multiple images in strong lensing (SL) clusters. We show that by combining (a) an arc-finding (or source extracting) program, (b) photometric redshift…

Cosmology and Nongalactic Astrophysics · Physics 2020-01-08 Mauricio Carrasco , Adi Zitrin , Gregor Seidel

We explore the accuracy of the clustering-based redshift inference within the MICE2 simulation. This method uses the spatial clustering of galaxies between a spectroscopic reference sample and an unknown sample. The goal of this study is to…

Cosmology and Nongalactic Astrophysics · Physics 2017-12-27 V. Scottez , A. Benoit-Lévy , J. Coupon , O. Ilbert , Y. Mellier

We describe a large sample of 598 galaxy clusters and rich groups discovered in the data of the Faint Sky Variability Survey. The clusters have been identified using a fully automated, semi-parametric technique based on a maximum likelihood…

Astrophysics · Physics 2009-11-11 Ilona K. Soechting , Mark E. Huber , Roger G. Clowes , Steve B. Howell

This is the fourth of a series of papers on low X-ray luminosity galaxy clusters. The sample comprises 45 galaxy clusters with X-ray luminosities fainter than 0.7 10$^{44}$ erg s$^{-1}$ at redshifts lower than 0.2 in the regions of the…

Astrophysics of Galaxies · Physics 2019-05-17 A. L. O'Mill , M. V. Alonso , C. Valotto , J. L. Nilo Castellón

A compact group (CG) is a kind of special galaxy system where the galaxy members are separated at the distances of the order of galaxy size. The strong interaction between the galaxy members makes CGs ideal labs for studying the…

Astrophysics of Galaxies · Physics 2021-01-19 Yunliang Zheng , Shiyin Shen

Super-sample covariance (SSC) is the dominant source of statistical error on large scale structure (LSS) observables for both current and future galaxy surveys. In this work, we concentrate on the SSC of cluster counts, also known as sample…

Cosmology and Nongalactic Astrophysics · Physics 2018-07-06 Fabien Lacasa , Marcos Lima , Michel Aguena

WL measurements have well-known shear estimation biases, which can be partially corrected for with the use of image simulations. We present an analysis of simulated images that mimic HST/ACS observations of high-redshift galaxy clusters,…

Cosmology and Nongalactic Astrophysics · Physics 2020-08-26 B. Hernandez-Martin , T. Schrabback , H. Hoekstra , N. Martinet , J. Hlavacek-Larrondo , L. E. Bleem , M. D. Gladders , B. Stalder , A. A. Stark , M. Bayliss

Spectral clustering is a novel clustering method which can detect complex shapes of data clusters. However, it requires the eigen decomposition of the graph Laplacian matrix, which is proportion to $O(n^3)$ and thus is not suitable for…

Machine Learning · Computer Science 2013-07-02 Nguyen Lu Dang Khoa , Sanjay Chawla

We describe the target selection and resulting properties of a spectroscopic sample of luminous, red galaxies (LRG) from the imaging data of the Sloan Digital Sky Survey (SDSS). These galaxies are selected on the basis of color and…

We compare the statistical properties of giant gravitationally lensed arcs produced in matched simulated and observed cluster samples. The observed sample consists of 10 X-ray selected clusters at redshifts z ~ 0.2 imaged with HST by Smith…

Intrinsic alignments of galaxies have been shown to contaminate weak gravitational lensing observables on linear scales, $r>$ 10 $h^{-1}$Mpc, but studies of alignments in the non-linear regime have thus far been inconclusive. We present an…

Cosmology and Nongalactic Astrophysics · Physics 2016-11-29 Nora Elisa Chisari , Rachel Mandelbaum , Michael A. Strauss , Eric Huff , Neta Bahcall

In this work we present combined optical and X-ray cluster detection methods in an area near the North Galactic Pole area, previously covered by the SDSS and 2dF optical surveys. The same area has been covered by shallow ($\sim 1.8$…

High-redshift clusters of galaxies are amongst the largest cosmic structures. Their properties and evolution are key ingredients to our understanding of cosmology: to study the growth of structure from the inhomogeneities of the cosmic…

Astrophysics · Physics 2007-05-23 A. Fernandez-Soto , J. Bland-Hawthorn , J. I. Gonzalez-Serrano , R. Carballo

Galaxy clusters identified with optical imaging tend to suffer from projection effects, which impact richness (the number of member galaxies in a cluster) and lensing coherently. Physically unassociated galaxies can be mistaken as cluster…

The Sloan Digital Sky Survey (SDSS) and photometric/spectroscopic surveys in the GOODS-South field (the Chandra Deep Field-South, CDFS) are used to construct volume-limited, stellar mass-selected samples of galaxies at redshifts 0<z<1. The…

The results of a search for distant clusters of galaxies performed using the I-band data obtained by the ESO Imaging Survey (EIS) are presented. Cluster candidates are identified using a matched filter algorithm, that provides not only an…

Astrophysics · Physics 2007-05-23 M. Scodeggio , L. F. Olsen , L. N. da Costa