Download or read book Cross Correlating 2D and 3D Galaxy Surveys written by and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Galaxy surveys probe both structure formation and the expansion rate, making them promising avenues for understanding the dark universe. Photometric surveys accurately map the 2D distribution of galaxy positions and shapes in a given redshift range, while spectroscopic surveys provide sparser 3D maps of the galaxy distribution. We present a way to analyse overlapping 2D and 3D maps jointly and without loss of information. We represent 3D maps using spherical Fourier-Bessel (sFB) modes, which preserve radial coverage while accounting for the spherical sky geometry, and we decompose 2D maps in a spherical harmonic basis. In these bases, a simple expression exists for the cross-correlation of the two fields. One very powerful application is the ability to simultaneously constrain the redshift distribution of the photometric sample, the sample biases, and cosmological parameters. We use our framework to show that combined analysis of DESI and LSST can improve cosmological constraints by factors of ${\sim}1.2$ to ${\sim}1.8$ on the region where they overlap relative to identically sized disjoint regions. We also show that in the overlap of DES and SDSS-III in Stripe 82, cross-correlating improves photo-$z$ parameter constraints by factors of ${\sim}2$ to ${\sim}12$ over internal photo-$z$ reconstructions.

Download or read book Cross correlation Weak Lensing of SDSS Galaxy Clusters II written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We interpret and model the statistical weak lensing measurements around 130,000 groups and clusters of galaxies in the Sloan Digital Sky Survey presented by Sheldon et al. (2007). We present non-parametric inversions of the 2D shear profiles to the mean 3D cluster density and mass profiles in bins of both optical richness and cluster i-band luminosity. Since the mean cluster density profile is proportional to the cluster-mass correlation function, the mean profile is spherically symmetric by the assumptions of large-scale homogeneity and isotropy. We correct the inferred 3D profiles for systematic effects, including non-linear shear and the fact that cluster halos are not all precisely centered on their brightest galaxies. We also model the measured cluster shear profile as a sum of contributions from the brightest central galaxy, the cluster dark matter halo, and neighboring halos. We infer the relations between mean cluster virial mass and optical richness and luminosity over two orders of magnitude in cluster mass; the virial mass at fixed richness or luminosity is determined with a precision of (almost equal to) 13% including both statistical and systematic errors. We also constrain the halo concentration parameter and halo bias as a function of cluster mass; both are in good agreement with predictions from N-body simulations of LCDM models. The methods employed here will be applicable to deeper, wide-area optical surveys that aim to constrain the nature of the dark energy, such as the Dark Energy Survey, the Large Synoptic Survey Telescope and space-based surveys.

Download or read book The Large Scale Structures written by Stéphane Ilić and published by Springer. This book was released on 2014-06-13 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dark Energy and Dark Matter are among the greatest mysteries in modern cosmology. The present work explores in depth how large cosmic structures can help us unveil the nature of these components of the Universe. One the one hand, it focuses on a signature that Dark Energy imprints on the Cosmic Microwave Background through its impact on the time-evolution of gravitational potentials: the integrated Sachs-Wolfe (iSW) effect. Another cosmological background, the Cosmic Infrared Background, is considered for the first time in the study of the iSW effect and demonstrated to be a highly efficient and promising tracer. Changing the perspective on the problem, the use of superstructures for iSW detection is then extensively reviewed: using precise solutions to Einstein’s general relativity equations, the full iSW effect is computed, especially due to the cosmic voids predicted by the theory. Using measurements from the most recent data, it is subsequently shown how the iSW probes the solidity of the cosmological standard model. On the topic of Dark Matter, an original study is presented, showing that temperature measurements of the intergalactic medium shed light on the nature of Dark Matter particles, providing the tightest constraints on their decay properties.

Download or read book Cross correlation of Gravitational Lensing from DES Science Verification Data with SPT and Planck Lensing written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We measure the cross-correlation between weak lensing of galaxy images and of the cosmic microwave background (CMB). The effects of gravitational lensing on different sources will be correlated if the lensing is caused by the same mass fluctuations. We use galaxy shape measurements from 139 deg$^{2}$ of the Dark Energy Survey (DES) Science Verification data and overlapping CMB lensing from the South Pole Telescope (SPT) and Planck. The DES source galaxies have a median redshift of $z_{\rm med} {\sim} 0.7$, while the CMB lensing kernel is broad and peaks at $z{\sim}2$. The resulting cross-correlation is maximally sensitive to mass fluctuations at $z{\sim}0.44$. Assuming the Planck 2015 best-fit cosmology, the amplitude of the DES$\times$SPT cross-power is found to be $A = 0.88 \pm 0.30$ and that from DES$\times$Planck to be $A = 0.86 \pm 0.39$, where $A=1$ corresponds to the theoretical prediction. These are consistent with the expected signal and correspond to significances of $2.9 \sigma$ and $2.2 \sigma$ respectively. We demonstrate that our results are robust to a number of important systematic effects including the shear measurement method, estimator choice, photometric redshift uncertainty and CMB lensing systematics. Significant intrinsic alignment of galaxy shapes would increase the cross-correlation signal inferred from the data; we calculate a value of $A = 1.08 \pm 0.36$ for DES$\times$SPT when we correct the observations with a simple IA model. With three measurements of this cross-correlation now existing in the literature, there is not yet reliable evidence for any deviation from the expected LCDM level of cross-correlation, given the size of the statistical uncertainties and the significant impact of systematic errors, particularly IAs. We provide forecasts for the expected signal-to-noise of the combination of the five-year DES survey and SPT-3G.

Download or read book Impact of Gravitational Lensing on Cosmology IAU S225 written by International Astronomical Union. Symposium and published by Cambridge University Press. This book was released on 2005-09-05 with total page 478 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains the proceedings of the International Astronomical Union Symposium no. 225, held in July 2004 at the Ecole Polytechnique Federale de Lausanne (EPFL), in Lausanne, Switzerland. The meeting focused on the applications of gravitational lensing to cosmological physics, and this book summarizes the most recent theoretical and observational developments. With chapters written by leading scientists in the field, this is a valuable resource for professional astronomers and graduate students in astronomy, physics and astro-particle physics.

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 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 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 Interferometry and Synthesis in Radio Astronomy written by A. Richard Thompson and published by Wiley-Interscience. This book was released on 1986-04-28 with total page 568 pages. Available in PDF, EPUB and Kindle. Book excerpt: A unified description of the theory and practice of radio interferometry and synthesis mapping techniques as they apply to astronomy and geology. Beginning with an historical review, it goes on to provide a detailed description of all aspects of radio inferometry, from basic principles through instrumental design to data reduction. Over 450 original papers and monographs are cited.

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 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 The Large Scale Structure of the Universe written by P. J. E. Peebles and published by Princeton University Press. This book was released on 2020-09-15 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt: The classic account of the structure and evolution of the early universe from Nobel Prize–winning physicist P. J. E. Peebles An instant landmark on its publication, The Large-Scale Structure of the Universe remains the essential introduction to this vital area of research. Written by one of the world's most esteemed theoretical cosmologists, it provides an invaluable historical introduction to the subject, and an enduring overview of key methods, statistical measures, and techniques for dealing with cosmic evolution. With characteristic clarity and insight, P. J. E. Peebles focuses on the largest known structures—galaxy clusters—weighing the empirical evidence of the nature of clustering and the theories of how it evolves in an expanding universe. A must-have reference for students and researchers alike, this edition of The Large-Scale Structure of the Universe introduces a new generation of readers to a classic text in modern cosmology.

Download or read book Fundamentals of Galaxy Dynamics Formation and Evolution written by Ignacio Ferreras and published by UCL Press. This book was released on 2019-04-02 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt: Galaxies, along with their underlying dark matter halos, constitute the building blocks of structure in the Universe. Of all fundamental forces, gravity is the dominant one that drives the evolution of structures from small density seeds at early times to the galaxies we see today. The interactions among myriads of stars, or dark matter particles, in a gravitating structure produce a system with fascinating connotations to thermodynamics, with some analogies and some fundamental differences. Ignacio Ferreras presents a concise introduction to extragalactic astrophysics, with emphasis on stellar dynamics, and the growth of density fluctuations in an expanding Universe. Additional chapters are devoted to smaller systems (stellar clusters) and larger ones (galaxy clusters). Fundamentals of Galaxy Dynamics, Formation and Evolution is written for advanced undergraduates and beginning postgraduate students, providing a useful tool to get up to speed in a starting research career. Some of the derivations for the most important results are presented in detail to enable students appreciate the beauty of maths as a tool to understand the workings of galaxies. Each chapter includes a set of problems to help the student advance with the material.

Download or read book An Introduction to Modern Cosmology written by Andrew Liddle and published by John Wiley & Sons. This book was released on 2015-04-27 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt: An Introduction to Modern Cosmology Third Edition is an accessible account of modern cosmological ideas. The Big Bang Cosmology is explored, looking at its observational successes in explaining the expansion of the Universe, the existence and properties of the cosmic microwave background, and the origin of light elements in the universe. Properties of the very early Universe are also covered, including the motivation for a rapid period of expansion known as cosmological inflation. The third edition brings this established undergraduate textbook up-to-date with the rapidly evolving observational situation. This fully revised edition of a bestseller takes an approach which is grounded in physics with a logical flow of chapters leading the reader from basic ideas of the expansion described by the Friedman equations to some of the more advanced ideas about the early universe. It also incorporates up-to-date results from the Planck mission, which imaged the anisotropies of the Cosmic Microwave Background radiation over the whole sky. The Advanced Topic sections present subjects with more detailed mathematical approaches to give greater depth to discussions. Student problems with hints for solving them and numerical answers are embedded in the chapters to facilitate the reader’s understanding and learning. Cosmology is now part of the core in many degree programs. This current, clear and concise introductory text is relevant to a wide range of astronomy programs worldwide and is essential reading for undergraduates and Masters students, as well as anyone starting research in cosmology. The accompanying website for this text, http://booksupport.wiley.com, provides additional material designed to enhance your learning, as well as errata within the text.

Download or read book Handbook of Statistical Analysis and Data Mining Applications written by Ken Yale and published by Elsevier. This book was released on 2017-11-09 with total page 824 pages. Available in PDF, EPUB and Kindle. Book excerpt: Handbook of Statistical Analysis and Data Mining Applications, Second Edition, is a comprehensive professional reference book that guides business analysts, scientists, engineers and researchers, both academic and industrial, through all stages of data analysis, model building and implementation. The handbook helps users discern technical and business problems, understand the strengths and weaknesses of modern data mining algorithms and employ the right statistical methods for practical application. This book is an ideal reference for users who want to address massive and complex datasets with novel statistical approaches and be able to objectively evaluate analyses and solutions. It has clear, intuitive explanations of the principles and tools for solving problems using modern analytic techniques and discusses their application to real problems in ways accessible and beneficial to practitioners across several areas—from science and engineering, to medicine, academia and commerce. - Includes input by practitioners for practitioners - Includes tutorials in numerous fields of study that provide step-by-step instruction on how to use supplied tools to build models - Contains practical advice from successful real-world implementations - Brings together, in a single resource, all the information a beginner needs to understand the tools and issues in data mining to build successful data mining solutions - Features clear, intuitive explanations of novel analytical tools and techniques, and their practical applications

Download or read book Cosmic Magnetic Fields IAU S259 written by International Astronomical Union. Symposium and published by Cambridge University Press. This book was released on 2009-06-11 with total page 716 pages. Available in PDF, EPUB and Kindle. Book excerpt: IAU Symposium 259 presents the first interdisciplinary, comprehensive review of the role of cosmic magnetic fields, involving astronomers and physicists from across the community. Offering both theoretical and observational topics ranging from Earth's habitability to the origin of the universe, this is an invaluable summary for researchers and graduate students.

Download or read book Statistics of the Galaxy Distribution written by Vicent J. Martinez and published by CRC Press. This book was released on 2001-12-20 with total page 451 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the last decade, statisticians have developed new statistical tools in the field of spatial point processes. At the same time, observational efforts have yielded a huge amount of new cosmological data to analyze. Although the main tools in astronomy for comparing theoretical results with observation are statistical, in recent years, cosmologis