Download or read book Cross correlation Cluster Cosmology written by Ying Zu and published by . This book was released on 2013 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt: To explain cosmic acceleration, most MG theories rely on an extra scalar field on top of the metric tensor field, mediating a "fifth" force on intermediate scales. However, photons do not respond to the scalar field, so there will be a mismatch between lensing and dynamical mass estimates if gravity is modified on relevant scales. Since GR has to be recovered in high density regions to evade stringent tests in the solar system and binary pulsars, MG theories generally invoke some "screening" mechanisms to either make the effective mass of the scalar field environment-dependent (Chameleon mechanism) or suppress the scalar field close to sources (Vainshtein mechanism). I investigate the impact of MG on the GIK profiles around massive clusters using two suites of MG simulations, namely, the f(R) and Galileon models, which employ the Chameleon and Vainshtein screening mechanisms, respectively. For clusters of M~1014h-1Msun at z~0.25, I find ~100-200 km/s enhancement in the characteristic infall velocity and ~50-100 km/s broadening in the radial and tangential velocity dispersions at r~5 Mpc compared to GR predictions. These deviations from GR are detectable via the GIK-modeling of ξcgs measured from existing and future galaxy redshift surveys.
Download or read book Cosmology with Cluster galaxy Cross correlations and Topics in Assembly Bias written by Andrés Nicolas Salcedo and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Cross correlation Weak Lensing of SDSS Galaxy Clusters I written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the first in a series of papers on the weak lensing effect caused by clusters of galaxies in Sloan Digital Sky Survey. The photometrically selected cluster sample, known as MaxBCG, includes (almost equal to)130,000 objects between redshift 0.1 and 0.3, ranging in size from small groups to massive clusters. We split the clusters into bins of richness and luminosity and stack the surface density contrast to produce mean radial profiles. The mean profiles are detected over a range of scales, from the inner halo (25 kpc/h) well into the surrounding large scale structure (30 Mpc/h), with a significance of 15 to 20 in each bin. The signal over this large range of scales is best interpreted in terms of the cluster-mass cross-correlation function. We pay careful attention to sources of systematic error, correcting for them where possible and bounding them where not. We find that the profiles scale strongly with richness and luminosity. We find the signal within a given richness bin depends upon luminosity, suggesting that luminosity is more closely correlated with mass than galaxy counts. We split the samples by redshift but detect no significant evolution. The profiles are not well described by power laws. In a subsequent series of papers we invert the profiles to three-dimensional mass profiles, show that they are well fit by a halo model description, measure mass-to-light ratios and provide a cosmological interpretation.
Download or read book Galaxy QSO Cross correlations written by Joshua Gene Nollenberg and published by . This book was released on 2004 with total page 544 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Correlations and Clustering Phenomena in Subatomic Physics written by M.N. Harakeh and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt: In many areas of physics, such as astrophysics, solid-state physics, nuclear physics and particle physics, a major outstanding problem is a better understanding of corre lation phenomena. While in most cases the average properties of a system are rather well understood, the correlations and the resulting clustering are poorly understood. They are reflections of the force mediating the interaction among the constituents and play essential roles in determining the structure of a physical system. At the largest scales, in astrophysics, it has recently been realized that there are huge voids in space and almost all matter is concentrated on filaments, raising interesting questions concerning the origin of this clustering of matter. In nuclear physics corre lation phenomena are important in all its subfields. It has been realized that so-called fluctuations in the one-particle density, which are a manifestation of nucleon-nucleon correlations, are crucial. These are important for an understanding of heavy-ion reac tions. This is the subject of modern quantum transport theories. Correlations are also crucial in the description of the high momentum components as observed in quasi-elastic knock-out reactions.
Download or read book Cross correlations in the Dark Energy Survey written by Pauline Eva Vielzeuf and published by . This book was released on 2018 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the past decades, we have been the witnesses of unprecedented advancements in the understanding of our universe dynamics and evolution. Indeed, together with the theory General Relativity (GR) by Albert Einstein at the beginning of the 1900's, the improvement of observational tools have led to the establishment of the standard model of cosmology the so-called ∧-cold-Dark-Matter model (∧CDM) that is so far the simplest model that describes best our universe considering observations. However, this standard model suffers from caveats, more specifically the presence in the theory of two dark components, Dark Energy and Dark Matter. Understanding the mystery behind these two components have become the leading objective of observational cosmology today, and of current experiments, as it is the case of the Dark Energy Survey (DES), that will after 5 years of observations image about 300 million galaxies with an unprecedented depth covering one eighth of the sky (5000 sq. deg.). This thesis is based on the analysis of the first year of observation of DES (DESY1) and more in particular on the use of cross-correlation techniques in cosmological analyses. Here, we expose two of different possible use of cross-correlation. Namely, we first show how cross-correlation techniques has been employed as a tool to infer redshift distribution of objects using the socalled clustering-redshift methodologies. And moreover how for the first time this techniques have entered in the cosmological analyses to correct the mean of the redshift distributions of the DESY1 galaxy catalog with shapes (the weak lensing sample) inferred by typical photometric techniques. We explain how using simulation we have evaluated systematics errors induced by our overall methodology and present the full methodology employed for redshift distribution determination of the DESY1 Weak lensing sample. In a second time, we expose how we have been using cross-correlations as a probe of ∧CDM cosmology using in one hand cross-correlation between cosmic voids identified in the DESY1 catalogs and the lensing map from the Planck satellite and on the other hand simulated ∧CDM cosmology. More specifically, recent results have suggested an excess signal in the observed void catalogs imprint in the Cosmic Microwave Background temperature maps with respect to simulated ∧CDM cosmology, we reiterate the procedure using this time the lensing maps of the CMB. After optimizing our void catalogs in simulation, looking for population of voids responsible for the more significant detection,we could detect the imprint of DESY1 cosmic voids with a significance of ̃ 7 – 12ơ with a discrepancy of ̃ 3 – 9ơ with respect to ∧CDM simulations.
Download or read book Precision Cosmology with Galaxy Cluster Surveys written by Hao-Yi Wu and published by Stanford University. This book was released on 2011 with total page 234 pages. Available in PDF, EPUB and Kindle. Book excerpt: The acceleration of the universe, which is often attributed to "dark energy, " has posed one of the main challenges to fundamental physics. Galaxy clusters provide one of the most sensitive probes of dark energy because their abundance reflects the growth rate of large-scale structure and the expansion rate of the universe. Several large galaxy cluster surveys will soon provide tremendous statistical power to constrain the properties of dark energy; however, the constraining power of these surveys will be determined by how well systematic errors are controlled. Of these systematic errors, the dominant one comes from inferring cluster masses using observable signals of clusters, the so-called "observable--mass distribution." This thesis focuses on extracting dark energy information from forthcoming large galaxy cluster surveys, including how we maximize the cosmological information, how we control important systematics, and how precisely we need to calibrate theoretical models. We study how multi-wavelength follow-up observations can improve cluster mass calibration in optical surveys. We also investigate the impact of theoretical uncertainties in calibrating the spatial distributions of galaxy clusters on dark energy constraints. In addition, we explore how the formation history of galaxy clusters impacts the self-calibration of cluster mass. In addition, we use N-body simulations to develop a new statistical sample of cluster-size halos in order to further understand the observable--mass distribution. We study the completeness of subhalos in our cluster sample by comparing them with the satellite galaxies in the Sloan Digital Sky Survey. We also study how subhalo selections impact the inferred correlation between formation time and optical mass tracers, including cluster richness and velocity dispersion.
Download or read book Cosmology from Large Scale Galaxy Clustering and Galaxy Galaxy Lensing with Dark Energy Survey Science Verification Data written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We present cosmological constraints from the Dark Energy Survey (DES) using a combined analysis of angular clustering of red galaxies and their cross-correlation with weak gravitational lensing of background galaxies. We use a 139 square degree contiguous patch of DES data from the Science Verification (SV) period of observations. Using large scale measurements, we constrain the matter density of the Universe as $\Omega_m = 0.31 \pm 0.09$ and the clustering amplitude of the matter power spectrum as $\sigma_8 = 0.74 +\pm 0.13$ after marginalizing over seven nuisance parameters and three additional cosmological parameters. This translates into $S_8$ = $\sigma_8(\Omega_m/0.3)^{0.16} = 0.74 \pm 0.12$ for our fiducial lens redshift bin at 0.35
Download or read book Probing Cosmic Dark Matter and Dark Energy with Weak Gravitational Lensing Statistics written by Masato Shirasaki and published by Springer. This book was released on 2015-11-18 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this book the applicability and the utility of two statistical approaches for understanding dark energy and dark matter with gravitational lensing measurement are introduced. For cosmological constraints on the nature of dark energy, morphological statistics called Minkowski functionals (MFs) to extract the non-Gaussian information of gravitational lensing are studied. Measuring lensing MFs from the Canada–France–Hawaii Telescope Lensing survey (CFHTLenS), the author clearly shows that MFs can be powerful statistics beyond the conventional approach with the two-point correlation function. Combined with the two-point correlation function, MFs can constrain the equation of state of dark energy with a precision level of approximately 3–4 % in upcoming surveys with sky coverage of 20,000 square degrees. On the topic of dark matter, the author studied the cross-correlation of gravitational lensing and the extragalactic gamma-ray background (EGB). Dark matter annihilation is among the potential contributors to the EGB. The cross-correlation is a powerful probe of signatures of dark matter annihilation, because both cosmic shear and gamma-ray emission originate directly from the same dark matter distribution in the universe. The first measurement of the cross-correlation using a real data set obtained from CFHTLenS and the Fermi Large Area Telescope was performed. Comparing the result with theoretical predictions, an independent constraint was placed on dark matter annihilation. Future lensing surveys will be useful to constrain on the canonical value of annihilation cross section for a wide range of mass of dark matter annihilation. Future lensing surveys will be useful to constrain on the canonical value of annihilation cross section for a wide range of mass of dark matter.
Download or read book Cross correlation Weak Lensing of SDSS Galaxy Clusters III written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We present measurements of the excess mass-to-light ratio measured around MaxBCG galaxy clusters observed in the SDSS. This red sequence cluster sample includes objects from small groups with M200 H"5 x 1012h−1M{sub {circle_dot}} to clusters with M200 H"5 x 1015h−1M{sub {circle_dot}}. Using cross-correlation weak lensing, we measure the excess mass density profile above the universal mean [Delta]2!r) = [rho](r) -- {bar [rho]} for clusters in bins of richness and optical luminosity. We also measure the excess {sup 0.25}i-band luminosity density [Delta]l(r) = l(r) -- {bar {ell}}. For both mass and light, we de-project the profiles to produce 3D mass and light profiles over scales from 25h−1 kpc to 22h−1 Mpc. From these profiles we calculate the cumulative excess mass [Delta]M(r) and excess light [Delta]L(r) as a function of separation from the BCG. On small scales, where [rho](r)” {bar {rho}}, the integrated mass-to-light profile ([Delta]M/[Delta]L)(r) may be interpreted as the cluster mass-to-light ratio. We find the ([Delta]M/[Delta]L)200, the mass-to-light ratio within r200, scales with cluster mass as a power law with index 0.33±0.02. On large scales, where {rho}(r) H"{bar {rho}}, the [Delta]M/[Delta]L approaches an asymptotic value independent of scale or cluster richness. For small groups, the mean ([Delta]M/[Delta]L)200 is much smaller than the asymptotic value, while for large clusters ([Delta]M/[Delta]L)200 is consistent with the asymptotic value. This asymptotic value should be proportional to the mean mass-to-light ratio of the universe {l_angle}M/L{r_angle}. We find {l_angle}M/L{r_angle} b−2{sub M/L} = 362 ± 54h measured in the {sup 0.25}i-bandpass. The parameter b2{sub M/L} is primarily a function of the bias of the L H" L* galaxies used as light tracers, and should be of order unity. Multiplying by the luminosity density in the same bandpass we find [Omega]{sub m}b−2{sub M/L}= 0.20 ± 0.03, independent of the Hubble parameter.
Download or read book A Large area Cross correlation Study of High Galactic Latitude Soft and Hard X ray Skies written by and published by . This book was released on 1999 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: Galaxies, active, galaxies, clusters, general, cosmology, diffuse radiation, X-rays.
Download or read book Cosmological Physics written by J. A. Peacock and published by Cambridge University Press. This book was released on 1999 with total page 700 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive and authoritative introduction to contemporary cosmology for advanced undergraduate and graduate students.
Download or read book Cosmological Physics with Gravitational Lensing written by J. Thanh Van Tran and published by . This book was released on 2001 with total page 316 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book 3K SN s Clusters Hunting the Cosmological Parameters with Precision Cosmology written by Domingos Barbosa and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: A JENAM 2002 Workshop, Porto, Portugal, 3-5 September 2002
Download or read book Clusters of Galaxies written by William R. Oegerle and published by Cambridge University Press. This book was released on 1990 with total page 415 pages. Available in PDF, EPUB and Kindle. Book excerpt: Collected in this volume are the review papers from the Space Telescope Science Institute symposium on Clusters of Galaxies held in May 1989. Fifteen experts in the field have presented summaries of our current understanding of the formation and evolution of clusters and their constituent galaxies. Subjects covered include the existence and importance of subclustering, models of the evolution of clusters and the intracluster medium, the effect of the cluster environment on galaxies, observations of high redshift clusters, and the use of clusters as tracers of large scale structure. This book provides a timely focus for future observational and theoretical work on clusters of galaxies.
Download or read book Modern Cosmology written by Scott Dodelson and published by Academic Press. This book was released on 2003-03-13 with total page 462 pages. Available in PDF, EPUB and Kindle. Book excerpt: An advanced text for senior undergraduates, graduate students and physical scientists in fields outside cosmology. This is a self-contained book focusing on the linear theory of the evolution of density perturbations in the universe, and the anisotropiesin the cosmic microwave background.
Download or read book Confrontation of Cosmological Theories with Observational Data written by Malcolm S. Longair and published by Springer Science & Business Media. This book was released on 2013-03-07 with total page 365 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of IAU Symposium No. 63, held in Cracow, Poland, September 10-12, 1973
