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Optical Galaxy Cluster Detection Across A Wide Redshift Range
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Book Synopsis Optical Galaxy Cluster Detection Across a Wide Redshift Range by :
Download or read book Optical Galaxy Cluster Detection Across a Wide Redshift Range written by and published by . This book was released on 2009 with total page 131 pages. Available in PDF, EPUB and Kindle. Book excerpt: The past decade is one of the most exciting period in the history of physics and astronomy. The discovery of cosmic acceleration dramatically changed our understanding about the evolution and constituents of the Universe. To accommodate the new acceleration phase into our well established Big Bang cosmological scenario under the frame work of General Relativity, there must exist a very special substance that has negative pressure and make up about 73% of the total energy density in our Universe. It is called Dark Energy. For the first time people realized that the vast majority of our Universe is made of things that are totally different from the things we are made of. Therefore, one of the major endeavors in physics and astronomy in the coming years is trying to understand, if we can, the nature of dark energy. Understanding dark energy cannot be achieved from pure logic. We need empirical evidence to finally determine about what is dark energy. The better we can constrain the energy density and evolution of the dark energy, the closer we will get to the answer. There are many ways to constrain the energy density and evolution of dark energy, each of which leads to degeneracy in certain directions in the parameter space. Therefore, a combination of complimentary methods will help to reduce the degeneracies and give tighter constraints. Dark energy became dominate over matter in the Universe only very recently (at about z (almost equal to) 1.5) and will affect both the cosmological geometry and large scale structure formation. Among the various experiments, some of them constrain the dark energy mainly via geometry (such as CMB, Supernovae) while some others provides constraints from both structures and geometry (such as BAO, Galaxy Clusters) Galaxy clusters can be used as a sensitive probe for cosmology. A large cluster catalog that extends to high redshift with well measured masses is indispensable for precisely constraining cosmological parameters. Detecting clusters in optical bands is very efficient. Multi-color CCD photometry allows combined detection and redshift estimation for clusters across broad redshift ranges. However, the lack of precise information about galaxy positions along the line of sight leads to contamination by projection, which plagues both cluster detection and the measurement of their properties. The dominance of red sequence galaxies, tightly clustered along the E/S0 ridgeline, provides a powerful method for de-projecting field galaxies. We developed an Error Corrected Gaussian Mixture Model to fit the galaxies color distribution around clusters by taking into account the measurement errors. By this technique, we can detect the red sequence color clustering and extract unbiased information about the evolution of the red sequence ridgeline and its width. Precision measurements of ridgelines yields better estimates of cluster richness and possibly their dynamical state, leading to better estimates of cluster mass. By using the red sequence clustering in color space identified from the Error Corrected Gaussian Mixture Model, together with the projected NFW filter in the projected RA/DEC plane, we developed a new and efficient cluster finding algorithm that can reliably detect galaxy clusters across the redshift range from 0.1 to 1.4. We have also run the cluster finder on legacy SDSS DR7 data and assembled an approximately volume limited cluster catalog across redshifts from 0.1 to 0.5. The algorithm has been tested against a Monte Carlo mock catalog, showing the identified clusters are highly complete and pure. With the completion of this thesis, we build the first and essential step towards precision cluster cosmology. Meanwhile, the large optical cluster catalog across a wide redshift range makes possible the systematic and detailed investigation of cluster formation and evolution.
Book Synopsis Brightest Cluster Galaxies: Optical Properties at Intermediate Redshift by :
Download or read book Brightest Cluster Galaxies: Optical Properties at Intermediate Redshift written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Galaxies grow and evolve via the repeated process of hierarchical merging, with smaller galaxies being cannibalized by larger and correspondingly brighter ones. Thus in galaxy clusters it is the brightest cluster galaxy (BCG) that lies at the top of the galaxian food chain and deep within the cluster potential the BCG grows to become one of the most massive galaxies in the universe. Baryonic feedback processes associated with the formation of the BCG (eg., AGN, star formation, stellar winds and chemical enrichment) affect the balance between heating and cooling of the intra-cluster medium (ICM) which in turn, through replenishment of the cold gas reservoir of the BCG, feeds back on these processes. This interconnection between the BCG and the state of the cluster gas has direct implications for theories of both galaxy and cluster evolution. Thanks to recent advances in observational techniques it has become possible to study the link between BCG and host cluster properties across a wide range of multi-wavelength information. Using deep imaging data taken with the Canada-France-Hawaii Telescope as part of the Canadian Cluster Comparison Project. (CCCP). we examine the surface brightness distributions in g' and r' of 28 BCGs in a redshift range 0.15 z 0.55 residing in massive clusters with Tx> 5 and compare them to the global X-ray properties of their hosts. We fit R1/4 models to the surface brightness profiles and find that the Kormendy relation of BCGs, when corrected for passive evolution. is consistent with that of the local elliptical population. We identify a subset of BCGs with extraordinarily blue centers (0.1
Book Synopsis Brightest Cluster Galaxies by : Christopher John Bildfell
Download or read book Brightest Cluster Galaxies written by Christopher John Bildfell and published by . This book was released on 2006 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Galaxies grow and evolve via the repeated process of hierarchical merging, with smaller galaxies being cannibalized by larger and correspondingly brighter ones. Thus in galaxy clusters it is the brightest cluster galaxy (BCG) that lies at the top of the galaxian food chain and deep within the cluster potential the BCG grows to become one of the most massive galaxies in the universe. Baryonic feedback processes associated with the formation of the BCG (eg., AGN, star formation, stellar winds and chemical enrichment) affect the balance between heating and cooling of the intra-cluster medium (ICM) which in turn, through replenishment of the cold gas reservoir of the BCG, feeds back on these processes. This interconnection between the BCG and the state of the cluster gas has direct implications for theories of both galaxy and cluster evolution. Thanks to recent advances in observational techniques it has become possible to study the link between BCG and host cluster properties across a wide range of multi-wavelength information. Using deep imaging data taken with the Canada-France-Hawaii Telescope as part of the Canadian Cluster Comparison Project. (CCCP). we examine the surface brightness distributions in g' and r' of 28 BCGs in a redshift range 0.15 z 0.55 residing in massive clusters with Tx> 5 and compare them to the global X-ray properties of their hosts. We fit R1/4 models to the surface brightness profiles and find that the Kormendy relation of BCGs, when corrected for passive evolution. is consistent with that of the local elliptical population. We identify a subset of BCGs with extraordinarily blue centers (0.1
Book Synopsis Brightest Cluster Galaxies by : Christopher John Bildfell
Download or read book Brightest Cluster Galaxies written by Christopher John Bildfell and published by . This book was released on 2006 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt: Galaxies grow and evolve via the repeated process of hierarchical merging, with smaller galaxies being cannibalized by larger and correspondingly brighter ones. Thus in galaxy clusters it is the brightest cluster galaxy (BCG) that lies at the top of the galaxian food chain and deep within the cluster potential the BCG grows to become one of the most massive galaxies in the universe. Baryonic feedback processes associated with the formation of the BCG (eg., AGN, star formation, stellar winds and chemical enrichment) affect the balance between heating and cooling of the intra-cluster medium (ICM) which in turn, through replenishment of the cold gas reservoir of the BCG, feeds back on these processes. This interconnection between the BCG and the state of the cluster gas has direct implications for theories of both galaxy and cluster evolution. Thanks to recent advances in observational techniques it has become possible to study the link between BCG and host cluster properties across a wide range of multi-wavelength information. Using deep imaging data taken with the Canada-France-Hawaii Telescope as part of the Canadian Cluster Comparison Project. (CCCP). we examine the surface brightness distributions in g' and r' of 28 BCGs in a redshift range 0.15 z 0.55 residing in massive clusters with Tx> 5 and compare them to the global X-ray properties of their hosts. We fit R1/4 models to the surface brightness profiles and find that the Kormendy relation of BCGs, when corrected for passive evolution. is consistent with that of the local elliptical population. We identify a subset of BCGs with extraordinarily blue centers (0.1
Book Synopsis The XMM-BCS Galaxy Cluster Survey by :
Download or read book The XMM-BCS Galaxy Cluster Survey written by and published by . This book was released on 2011 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: The XMM-Newton - Blanco Cosmology Survey project (XMM-BCS) is a coordinated X-ray, optical and mid-infrared cluster survey in a field also covered by Sunyaev-Zel dovich effect (SZE) surveys by the South Pole Telescope and the Atacama Cosmology Telescope. The aim of the project is to study the cluster population in a 14 deg2 field (center: [alpha] H"23:29:18.4, [delta] H"-54:40:33.6). The uniform multi-wavelength coverage will also allow us for the first time to comprehensively compare the selection function of the different cluster detection approaches in a single test field and perform a cross-calibration of cluster scaling relations. In this work, we present a catalog of 46 X-ray selected clusters from the initial 6 deg2 survey core. We describe the XMM-BCS source detection pipeline and derive physical properties of the clusters. We provide photometric redshift estimates derived from the BCS imaging data and spectroscopic redshift measurements for a low redshift subset of the clusters. The photometric redshift estimates are found to be unbiased and in good agreement with the spectroscopic values. Our multi-wavelength approach gives us a comprehensive look at the cluster and group population up to redshifts z H"1. The median redshift of the sample is 0.47 and the median mass M500 H"1 x 1014 M{sub {circle_dot}} (H"2 keV). From the sample, we derive the cluster log N - log S using an approximation to the survey selection function and find it in good agreement with previous studies. We compare optical mass estimates from the Southern Cosmology Survey available for part of our cluster sample with our estimates derived from the X-ray luminosity. Weak lensing masses available for a subset of the cluster sample are in agreement with our estimates. Optical masses based on cluster richness and total optical luminosity are found to be significantly higher than the X-ray values. The present results illustrate the excellent potential of medium-deep, X-ray surveys to deliver cluster samples for cosmological modelling. In combination with available multi-wavelength data in optical, near-infrared and SZE, this will allow us to probe the dependence of the selection functions on relevant cluster observables and provide thus an important input for upcoming large-area multi-wavelength cluster surveys.
Download or read book Looking Wider and Further written by and published by . This book was released on 2016 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: Galaxy clusters are rare objects in the universe, but on-going wide field optical surveys are identifying many thousands of them to redshift 1.0 and beyond. Using early data from the Dark Energy Survey (DES) and publicly released data from the Sloan Digital Sky Survey (SDSS), this dissertation explores the evolution of cluster galaxies in the redshift range from 0 to 1.0. As it is common for deep wide field sky surveys like DES to struggle with galaxy detection efficiency at cluster core, the first component of this dissertation describes an efficient package that helps resolving the issue. The second part focuses on the formation of cluster galaxies. The study quantifies the growth of cluster bright central galaxies (BCGs), and argues for the importance of merging and intra-cluster light production during BCG evolution. An analysis of cluster red sequence galaxy luminosity function is also performed, demonstrating that the abundance of these galaxies is mildly dependent on cluster mass and redshift. The last component of the dissertation characterizes the properties of galaxy filaments to help understanding cluster environments.
Book Synopsis A Multi-wavelength Study of Optically Selected Galaxy Clusters from the Blanco Cosmology Survey by : Lindsey Ellen Bleem
Download or read book A Multi-wavelength Study of Optically Selected Galaxy Clusters from the Blanco Cosmology Survey written by Lindsey Ellen Bleem and published by . This book was released on 2013 with total page 117 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abundance measurements of galaxy clusters provide powerful constraints of cosmology. The observed distribution of clusters can potentially be used to disentangle whether the accelerated cosmic expansion can be explained by a modification to Einstein's theory of gravity or whether the explanation involves a new form of 'dark' energy. Such growth of structure measurements are both complementary to and provide an important cross-check of measurements of the geometry of the universe. There are two key requirements for cosmology with galaxy clusters: a census of these systems through cosmic time and the ability to connect the measured signal with the underlying mass of the galaxy cluster. In this era of large-area millimeter and optical wavelength surveys (including the South Pole Telescope (SPT) 2500-square-degree SZ-Survey and the Dark Energy Survey (DES)) where hundreds (mm-wave) to hundreds of thousands (optical) of clusters will be detected, the most serious limitation to cluster cosmology remains understanding and calibrating observable-mass relations. Combining cluster observables across wavelengths can both test and inform our knowledge of such scaling relations. As a pilot program for future explorations of the combined SPT and DES datasets, we explore the relation between the optical-richness, lambda, and SZ-signal for a sample of 567 optically-selected clusters from the Blanco Cosmology Survey, an ~ 80 square-degree survey located within the SPT-SZ survey. In this study we detect SZ-signal at increasing significance as a function of cluster richness but find that the recovered signal falls below expectations derived from models based on X-ray samples. We explore possible biases to our recovered signal and find that contamination from cluster members -- in particular radio and dust emission from galaxies--is small and that the majority of the discrepancy at the high mass end can be explained by errors in identifying the optical centers of clusters. The toolset developed here can be combined with future cluster catalogs from the Dark Energy Survey to help improve mass-richness scaling relations and ultimately constrain cosmological models.
Book Synopsis Submillimeter Imaging of High-redshift Galaxy Clusters by : Allison G. Noble
Download or read book Submillimeter Imaging of High-redshift Galaxy Clusters written by Allison G. Noble and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :Wayne Alan Barkhouse Publisher :National Library of Canada = Bibliothèque nationale du Canada ISBN 13 :9780612846548 Total Pages :484 pages Book Rating :4.8/5 (465 download)
Book Synopsis A Wide-field Imaging Survey of Low-redshift Galaxy Clusters [microform] by : Wayne Alan Barkhouse
Download or read book A Wide-field Imaging Survey of Low-redshift Galaxy Clusters [microform] written by Wayne Alan Barkhouse and published by National Library of Canada = Bibliothèque nationale du Canada. This book was released on 2003 with total page 484 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :National Aeronautics and Space Adm Nasa Publisher :Independently Published ISBN 13 :9781792941122 Total Pages :30 pages Book Rating :4.9/5 (411 download)
Book Synopsis The Universe at Moderate Redshift by : National Aeronautics and Space Adm Nasa
Download or read book The Universe at Moderate Redshift written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2019-01-03 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: The report covers the work done in the past year and a wide range of fields including properties of clusters of galaxies; topological properties of galaxy distributions in terms of galaxy types; patterns of gravitational nonlinear clustering process; development of a ray tracing algorithm to study the gravitational lensing phenomenon by galaxies, clusters and large-scale structure, one of whose applications being the effects of weak gravitational lensing by large-scale structure on the determination of q(0); the origin of magnetic fields on the galactic and cluster scales; the topological properties of Ly(alpha) clouds the Ly(alpha) optical depth distribution; clustering properties of Ly(alpha) clouds; and a determination (lower bound) of Omega(b) based on the observed Ly(alpha) forest flux distribution. In the coming year, we plan to continue the investigation of Ly(alpha) clouds using larger dynamic range (about a factor of two) and better simulations (with more input physics included) than what we have now. We will study the properties of galaxies on 1 - 100h(sup -1) Mpc scales using our state-of-the-art large scale galaxy formation simulations of various cosmological models, which will have a resolution about a factor of 5 (in each dimension) better than our current, best simulations. We will plan to study the properties of X-ray clusters using unprecedented, very high dynamic range (20,000) simulations which will enable us to resolve the cores of clusters while keeping the simulation volume sufficiently large to ensure a statistically fair sample of the objects of interest. The details of the last year's works are now described. Cen, Renyue and Ostriker, Jeremiah P. Goddard Space Flight Center NASA-CR-205473, NAS 1.26:205473 NAG5-2759...
Book Synopsis Internal Dynamics of Galaxy Clusters in the Red-Sequence Cluster Survey by : Kris Blindert
Download or read book Internal Dynamics of Galaxy Clusters in the Red-Sequence Cluster Survey written by Kris Blindert and published by . This book was released on 2006 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt: We compute the global dynamical properties of the clusters in our survey, such as velocity dispersion and mass, and use them to explore the properties of RCS clusters as functions of total cluster mass. In particular, we first examine the optical richness as an inexpensive proxy for mass. The calibration of this relation is an important ingredient in the construction of the cluster mass function, which is used to constrain cosmological parameters. Our relation and scatter are consistent with self-calibrated cosmological parameter results. We also study the cluster mass-to-light ratios, and how they scale with mass. We compare our results to other observations and to structure formation models. Although the scatter in this relation is large, we find agreement among remarkably different types of galaxy clusters and groups; however, current structure formation models do not accurately reproduce the variation of M/L with mass. We present a spectroscopic survey of clusters of galaxies, designed to explore the distribution of matter, and its relation to light, in these massive systems. Our sample is drawn from the Red-sequence Cluster Survey (RCS), and is composed of 33 clusters with a wide range of optical richness and a moderate range of redshift. We obtained spectra of 56 to 529 objects per cluster, which yielded over 3500 redshifts of which 1014 are cluster members. To account for survey incompleteness due to sparse sampling, we constructed several empirical corrections so that our redshift catalogue is suitable for use in dynamical analysis. To boost statistics and allow us to perform a more detailed dynamical analysis of clusters, we stack our data into "ensemble" clusters. Cosmological simulations predict a roughly universal density profile for dark matter haloes over many scales, and a relation between halo mass and the concentration of the profile. We analyse the ensembles using the jeans equations, and recover density profiles for several ensemble clusters of different masses. Although the sampling of our data at small radii is insufficient to constrain some quantities of interest such as the inner core slope of the density profile, we can constrain the concentrations and orbital anisotropies for the ensemble clusters. We find they agree with predictions and previous observations: namely, that galaxies in clusters follow roughly isotropic orbits, and the concentrations of cluster density profiles are consistent with the prediction one would obtain from their masses. We also estimate the variation of concentration with redshift, finding a slightly stronger evolution than expected.
Book Synopsis Clustering at High Redshift by : Alain Mazure
Download or read book Clustering at High Redshift written by Alain Mazure and published by . This book was released on 2000 with total page 528 pages. Available in PDF, EPUB and Kindle. Book excerpt: Annotation Astronomers, astrophysicists, and other scientists and researchers from laboratories, observatories, and universities throughout North America, Europe, Asia, and the Middle East present 60 contributions addressing clustering from low to high redshift; clustering measurements in surveys; IR and sub-mm surveys; theory and models; high-redshift clusters of galaxies; QSO absorption lines; primordial galaxies; clustering around QSOs and radio galaxies; and the physics of the intra-cluster medium. Approximately 40 poster sessions are also presented. Lacks an index. Annotation c. Book News, Inc., Portland, OR (booknews.com)
Book Synopsis Optical Galaxy Cluster Detection and Weak Gravitational Lensing Derived Galaxy Cluster Mass Functions by : Martha Milkeraitis
Download or read book Optical Galaxy Cluster Detection and Weak Gravitational Lensing Derived Galaxy Cluster Mass Functions written by Martha Milkeraitis and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Galaxy Cluster Detection with Optical and Infrared Imaging by : Rossella Licitra
Download or read book Galaxy Cluster Detection with Optical and Infrared Imaging written by Rossella Licitra and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Redshift Controversy by : George B. Field
Download or read book The Redshift Controversy written by George B. Field and published by Addison Wesley Longman. This book was released on 1973 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Optical Cluster-Finding with an Adaptive Matched-Filter Technique by :
Download or read book Optical Cluster-Finding with an Adaptive Matched-Filter Technique written by and published by . This book was released on 2007 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present a modified adaptive matched filter algorithm designed to identify clusters of galaxies in wide-field imaging surveys such as the Sloan Digital Sky Survey. The cluster-finding technique is fully adaptive to imaging surveys with spectroscopic coverage, multicolor photometric redshifts, no redshift information at all, and any combination of these within one survey. It works with high efficiency in multi-band imaging surveys where photometric redshifts can be estimated with well-understood error distributions. Tests of the algorithm on realistic mock SDSS catalogs suggest that the detected sample is H"85% complete and over 90% pure for clusters with masses above 1.0 x 1014h−1 M and redshifts up to z = 0.45. The errors of estimated cluster redshifts from maximum likelihood method are shown to be small (typically less that 0.01) over the whole redshift range with photometric redshift errors typical of those found in the Sloan survey. Inside the spherical radius corresponding to a galaxy overdensity of? = 200, we find the derived cluster richness?200 a roughly linear indicator of its virial mass M200, which well recovers the relation between total luminosity and cluster mass of the input simulation.
Book Synopsis Galaxy Cluster Detection Using Optimal Matched Filtering in Optical Bands by : Alexander Gelsin
Download or read book Galaxy Cluster Detection Using Optimal Matched Filtering in Optical Bands written by Alexander Gelsin and published by . This book was released on 2015 with total page 93 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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