Superclusters with thermal SZ effect surveys (original) (raw)
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Superclusters with thermal Sunyaev���Zel'dovich effect surveys
2002
We use a simple analytic model to compute the angular correlation function of clusters identified in upcoming thermal Sunyaev-Zel'dovich (SZ) effect surveys. We then compute the expected fraction of close pairs of clusters on the sky that are also close along the line of sight. We show how the expected number of cluster pairs as a function of redshift is sensitive to the assumed biasing relation between the cluster and the mass distribution. We find that, in a-cold dark matter model, the fraction of physically associated pairs is 70 per cent for angular separations smaller than 20 arcmin and clusters with a specific flux difference larger than 200 mJy at 143 GHz. The agreement of our analytic results with the Hubble volume N-body simulations is satisfactory. These results quantify the feasibility of using SZ surveys to compile catalogues of superclusters at any redshift.
Galaxy Clusters in Hubble Volume Simulations: Cosmological Constraints from Sky Survey Populations
The Astrophysical Journal, 2002
We use giga-particle N-body simulations to study galaxy cluster populations in Hubble volumes of ΛCDM (Ω m = 0.3, Ω Λ = 0.7) and τ CDM (Ω m = 1) world models. Mapping past light-cones of locations in the computational space, we create mock sky surveys of dark matter structure to z ≃ 1.4 over 10, 000 sq deg and to z ≃ 0.5 over two full spheres. Calibrating the Jenkins mass function at z = 0 with samples of ∼ 1.5 million clusters, we show that the fit describes the sky survey counts to ∼ < 20% acccuracy over all redshifts for systems more massive than poor galaxy groups (5 × 10 13 h −1 M ⊙ ).
The Cluster Lensing and Supernova Survey with Hubble: An Overview
The Astrophysical Journal Supplement Series, 2012
The Cluster Lensing And Supernova survey with Hubble (CLASH) is a 524-orbit Multi-Cycle Treasury Program to use the gravitational lensing properties of 25 galaxy clusters to accurately constrain their mass distributions. The survey, described in detail in this paper, will definitively establish the degree of concentration of dark matter in the cluster cores, a key prediction of structure formation models. The CLASH cluster sample is larger and less biased than current samples of space-based imaging studies of clusters to similar depth, as we have minimized lensing-based selection that favors systems with overly dense cores. Specifically, 20 CLASH clusters are solely X-ray selected. The X-ray-selected clusters are massive (kT > 5 keV) and, in most cases, dynamically relaxed. Five additional clusters are included for their lensing strength (θ Ein > 35 at z s = 2) to optimize the likelihood of finding highly magnified high-z (z > 7) galaxies. A total of 16 broadband filters, spanning the near-UV to near-IR, are employed for each 20-orbit campaign on each cluster. These data are used to measure precise (σ z ∼ 0.02(1 + z)) photometric redshifts for newly discovered arcs. Observations of each cluster are spread over eight epochs to enable a search for Type Ia supernovae at z > 1 to improve constraints on the time dependence of the dark energy equation of state and the evolution of supernovae. We present newly re-derived X-ray luminosities, temperatures, and Fe abundances for the CLASH clusters as well as a representative source list for MACS1149.6 + 2223 (z = 0.544).
The Astronomical Journal, 1998
We present a new, objectively selected, sample of galaxy overdensities detected in the Hubble Space Telescope Medium Deep Survey. These clusters/groups were found using an automated procedure which involved searching for statistically significant galaxy overdensities. The contrast of the clusters against the field galaxy population is increased when morphological data is used to search around bulge-dominated galaxies. In total, we present 92 overdensities above a probability threshold of 99.5%. We show, via extensive Monte Carlo simulations, that at least 60% of these overdensities are likely to be real clusters and groups and not random line-of-sight superpositions of galaxies. For each overdensity in the MDS cluster sample, we provide a richness and the average of the bulge-to-total ratio of galaxies within each system. This MDS cluster sample potentially contains some of the most distant clusters/groups ever detected, with about 25% of the overdensities having estimated redshifts z > ∼ 0.9. We have made this sample publicly available to facilitate spectroscopic confirmation of these clusters and help more detailed studies of cluster and galaxy evolution. We also report the serendipitous discovery of a new cluster close on the sky to the rich optical cluster CLl0016+16 at z = 0.546. This new overdensity, HST 001831+16208, may be coincident with both an X-ray source and a radio source. HST 001831+16208 is the third cluster/group discovered near to CL0016+16 and appears to strengthen the claims of Connolly et al. (1996) of superclustering at high redshift.
Clusters and superclusters in the Las Campanas redshift survey
Astronomy and Astrophysics, 2003
We use a 2-dimensional high-resolution density field of galaxies of the Las Campanas Redshift Survey (LCRS) with a smoothing length 0.8 h −1 Mpc to extract clusters and groups of galaxies, and a low-resolution field with a smoothing length 10 h −1 Mpc to find superclusters of galaxies. We study the properties of these density field (DF) clusters and superclusters, and compare the properties of the DF-clusters and superclusters with those of Abell clusters and superclusters and LCRS groups. We show that among the cluster samples studied the DF-cluster sample best describes the large-scale distribution of matter and the fine structure of superclusters. We calculate the DF-cluster luminosity function and find that clusters in high-density environments are about ten times more luminous than those in low-density environments. We show that the DF-superclusters that contain Abell clusters are richer and more luminous than the DF-superclusters without Abell clusters. The distribution of DF-clusters and superclusters shows the hierarchy of systems in the universe.
(DOI: will be inserted by hand later) Clusters and Superclusters in the Las Campanas Redshift Survey
2003
Abstract. We use a 2-dimensional high-resolution density field of galaxies of the Las Campanas Redshift Survey (LCRS) with a smoothing length 0.8 h −1 Mpc to extract clusters and groups of galaxies, and a low-resolution field with a smoothing length 10 h −1 Mpc to find superclusters of galaxies. We study the properties of these density field (DF) clusters and superclusters, and compare the properties of the DF-clusters and superclusters with those of Abell clusters and superclusters and LCRS groups. We show that among the cluster samples studied the DF-cluster sample best describes the large-scale distribution of matter and the fine structure of superclusters. We calculate the DF-cluster luminosity function and find that clusters in high-density environments are about ten times more luminous than those in low-density environments. We show that the DF-superclusters that contain Abell clusters are richer and more luminous than the DF-superclusters without Abell clusters. The distribut...
The Astronomical Journal, 2002
We present a comparison of Abell and Automated Plate Measuring Facility (APM) clusters of galaxies as tracers of the large scale structure of the Universe. We investigate selection functions of both cluster catalogs, using samples of all clusters (including clusters with estimated redshifts), and samples of clusters with measured redshifts. We find that the distribution of rich superclusters, defined by all Abell and APM clusters, is similar in volume covered by both cluster samples. We show that the supercluster-void network can be traced with both cluster samples; the network has a well-defined period of ∼ 120 h −1 Mpc. We calculate the correlation function for Abell and APM cluster samples. However, the APM cluster sample with measured redshifts covers a small volume which contains only a few very rich superclusters. These superclusters surround one void and have exceptionally large mutual separations. Due to this property the secondary maximum of the correlation function of APM clusters with measured velocities is located at larger scales than corresponding feature in the correlation function of Abell clusters. We conclude that the APM sample is not representative for the large-scale structure as a whole due to the small space coverage. The Abell cluster catalog is presently the best sample to investigate the large-scale distribution of high-density regions in the Universe. We present a catalog of superclusters of galaxies, based on APM clusters up to a redshift z lim = 0.13. Subject headings: cosmology: observations -large-scale structure of the Universe-cosmology:
4 Clusters and Superclusters in the Sloan Survey
2016
We find clusters and superclusters of galaxies using the Data Release 1 of the Sloan Digital Sky Survey. We calculate a low-resolution density field with a smoothing length of 10 h −1 Mpc to extract superclusters of galaxies, and a high-resolution density field with a smoothing length of 0.8 h −1 Mpc to see the fine structure within superclusters. We found that clusters in a highdensity environment have luminosities that are about five times higher than the luminosities of clusters in a low-density environment. Numerical simulations show that in large underdense regions most particles form a rarefied population of pregalactic matter whereas in large overdense regions most particles form a clustered population in rich clusters. Simulations show also that very massive superclusters are great attractors and have small bulk motions. Less massive superclusters are smaller attractors and have much larger bulk motions.
Superclusters of galaxies from the 2dF redshift survey
Astronomy and Astrophysics, 2007
We use the 2dF Galaxy Redshift Survey data to compile catalogues of superclusters for the Northern and Southern regions of the 2dFGRS, altogether 543 superclusters at redshifts 0.009 ≤ z ≤ 0.2. We analyse methods of compiling supercluster catalogues and use results of the Millennium Simulation to investigate possible selection effects and errors. We find that the most effective method is the density field method using smoothing with an Epanechnikov kernel of radius 8 h −1 Mpc. We derive positions of the highest luminosity density peaks and find the most luminous cluster in the vicinity of the peak, this cluster is considered as the main cluster and its brightest galaxy the main galaxy of the supercluster. In catalogues we give equatorial coordinates and distances of superclusters as determined by positions of their main clusters. We also calculate the expected total luminosities of the superclusters.
Cluster Lensing And Supernova survey with Hubble (CLASH): An Overview
Arxiv preprint arXiv: …, 2011
The Cluster Lensing And Supernova survey with Hubble (CLASH) is a 524-orbit Multi-Cycle Treasury Program to use the gravitational lensing properties of 25 galaxy clusters to accurately constrain their mass distributions. The survey, described in detail in this paper, will definitively establish the degree of concentration of dark matter in the cluster cores, a key prediction of structure formation models. The CLASH cluster sample is larger and less biased than current samples of space-based imaging studies of clusters to similar depth, as we have minimized lensing-based selection that favors systems with overly dense cores. Specifically, 20 CLASH clusters are solely X-ray selected. The X-ray-selected clusters are massive (kT > 5 keV) and, in most cases, dynamically relaxed. Five additional clusters are included for their lensing strength (θ Ein > 35 at z s = 2) to optimize the likelihood of finding highly magnified high-z (z > 7) galaxies. A total of 16 broadband filters, spanning the near-UV to near-IR, are employed for each 20-orbit campaign on each cluster. These data are used to measure precise (σ z ∼ 0.02(1 + z)) photometric redshifts for newly discovered arcs. Observations of each cluster are spread over eight epochs to enable a search for Type Ia supernovae at z > 1 to improve constraints on the time dependence of the dark energy equation of state and the evolution of supernovae. We present newly re-derived X-ray luminosities, temperatures, and Fe abundances for the CLASH clusters as well as a representative source list for MACS1149.6 + 2223 (z = 0.544).