Download or read book Extracting Cosmological Information from Small Scales in Weak Gravitational Lensing Data written by Jose Manuel Zorrilla Matilla and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Second, we propose a novel measurement, that of the temperature dipole induced on the cosmic microwave background induced by the rotation of ionized gas around galaxies, as an additional observation to help constrain the distribution of baryonic matter on the smallest scales probed by WL experiments. The uncertainty in this distribution is a major theoretical systematic for future surveys. Third, we show how deep neural networks can be used to map pixel-level data into the cosmological parameters of interest, by-passing the previous compression step of measuring pre-designed statistics. We provide the first (simulation-based) credible contours based on neural networks applied to weak lensing data, and discuss how to interpret these models.
Download or read book Cosmological Inference with Cosmic Shear written by Peter Llewelyn Taylor and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 The Weak Gravitational Lensing of Light in Cosmological N body Simulations written by Andrew J. Barber and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Cosmological Information from Weak Gravitational Lensing written by Antonio C. C. Guimarães and published by . This book was released on 2003 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book From the Fermi Scale to Cosmology written by Alberto Salvio and published by Frontiers Media SA. This book was released on 2019-12-06 with total page 265 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Introduction to Gravitational Lensing written by Massimo Meneghetti and published by Springer Nature. This book was released on 2021-12-10 with total page 412 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book introduces the phenomenology of gravitational lensing in an accessible manner and provides a thorough discussion of the related astrophysical applications. It is intended for advanced undergraduates and graduate students who want to start working in this rapidly evolving field. This includes also senior researchers who are interested in ongoing or future surveys and missions such as DES, Euclid, WFIRST, LSST. The reader is guided through many fascinating topics related to gravitational lensing like the structure of our galaxy, the searching for exoplanets, the investigation of dark matter in galaxies and galaxy clusters, and several aspects of cosmology, including dark energy and the cosmic microwave background. The author, who has gained valuable experience as academic teacher, guides the readers towards the comprehension of the theory of gravitational lensing and related observational techniques by using simple codes written in python. This approach, beyond facilitating the understanding of gravitational lensing, is preparatory for learning the python programming language which is gaining large popularity both in academia and in the private sector.
Download or read book Data Analysis in Cosmology written by Vicent J. Martinez and published by Springer. This book was released on 2009-07-09 with total page 636 pages. Available in PDF, EPUB and Kindle. Book excerpt: The amount of cosmological data has dramatically increased in the past decades due to an unprecedented development of telescopes, detectors and satellites. Efficiently handling and analysing new data of the order of terabytes per day requires not only computer power to be processed but also the development of sophisticated algorithms and pipelines. Aiming at students and researchers the lecture notes in this volume explain in pedagogical manner the best techniques used to extract information from cosmological data, as well as reliable methods that should help us improve our view of the universe.
Download or read book Gravitational Lensing in Standard and Non standard Frameworks as a Probe for Precision Cosmology written by Michael A. Troxel and published by . This book was released on 2014 with total page 576 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gravitational lensing has been identified as a critical cosmological tool in studying the evolution of large scale structure in the universe as well as the nature of dark matter and dark energy. One of the primary physical systematics of weak lensing due to large scale structure (cosmic shear) is the intrinsic alignment (IA) of galaxies, which poses a barrier to precision weak lensing measurements. Methods for identifying and removing its effects on cosmological information are key to the success of weak lensing survey science goals. We have expanded model-independent techniques to isolate and remove the IA contamination from the lensing signal. These self-calibration techniques take advantage of complementary survey information to self-calibrate the lensing signal, which along with unique lensing and IA geometry and separation dependencies, allow us to reconstruct the IA correlations at the level of the spectrum and bispectrum. We have demonstrated that the self-calibration approach can reduce the IA bias over most relevant scale and redshift ranges by up to a factor of 10 or more. This could reduce a potential 10-20% bias in some cosmological information down to the 1-2% level. The self-calibration techniques have the added benefit of preserving the IA signal, which itself provides additional information that can be used in studying the formation and evolution of large scale structure in the universe. We have also identified a new source of intrinsic alignment contamination in cross-correlations with cosmic microwave background lensing and proposed a method to calibrate it, and we explored the potential of future surveys to measure directly various 2- and 3-point intrinsic alignment correlations. Finally, we have investigated the use of exact anisotropic and inhomogeneous models in general relativity for large- and small-scale structures in the universe, developing the frameworks necessary to analyze gravitational lensing in such models, and have compared them to observations, identifying potential sources of bias. We have found, for example, that ignoring substructure level anisotropies in structures could bias the lensing convergence, shear, and kinematic mass estimates by up to 10% or more. We conclude by presenting a numerical code package for calculations in such exact anisotropic and inhomogeneous models.
Download or read book Gravitational Lensing and Microlensing written by Silvia Mollerach and published by World Scientific. This book was released on 2002 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides a comprehensive and self-contained exposition of gravitational lensing phenomena.
Download or read book The Post Recombination Universe written by N. Kaiser and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 361 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume consists of invited talks and contributed papers presented at the NATO Advanced Study Institute "The Post Recombination Universe" which was held in Cambridge in the summer of 1987. There have, in recent years, been numerous meetings devoted to problems in observational cosmology. The attention given reflects the exciting rate of de velopment of the subject, and a survey of the proceedings from these symposia reveals that a great deal of emphasis has been given to consideration of the very early universe on the one hand, and to large scale structure in the universe at the present epoch on the other. The theme of this meeting was chosen to comple ment these efforts by focussing on the state of the universe at quite early times, but at those epochs which are still accessible to direct observations. The meet ing provided a broad coverage of the post recombination universe by drawing on experts from a wide variety of fields covering theory, background radiation fields and discrete sources at high redshift. Events in the moderately early universe will have left their mark in a great range of wavebands, from X-rays to the microwave region, and the evolution of the universe can be revealed by studies of the inter galactic medium, gravitational lensing and the abundance and clustering of high redshift sources. All of these subjects received much attention at the meeting, and the papers demonstrate the rich interplay between these areas in the rapidly expanding world of observational cosmology.
Download or read book Weak Gravitational Lensing Shear and Magnification Analysis of Hydrodynamic Simulations and Application to Weak Lensing Data written by Miyoung Choi and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In the main part of this dissertation we study the impact of baryonic processes and massive neutrinos on weak lensing peak statistics that can be used to constrain cosmological parameters. We use the BAHAMAS simulations, which self-consistently include baryonic processes and the effect of massive neutrino free-streaming on the evolution of structure formation. We construct synthetic weak lensing maps by ray-tracing through light-cones, specifically using the so-called aperture mass statistic. The peaks detected on the maps reflect the cumulative lensing signal from massive bound objects and general large scale structure of the Universe. In particular, we quantify the impact of the prescription for baryonic physics and a range of summed neutrino masses {0.06, 0.12, 0.24, 0.48} eV on the detected peaks, so that in future this uncertainty can be factored into studies using lensing peaks to constrain cosmological models. As higher neutrino mass tends to suppress the formation of massive structures in the Universe, the halo mass function and lensing peak counts are therefore modified as a function of M.,,, . Both baryonic physics and massive neutrinos impact on weak lensing peaks, depending on the mass range under consideration, and should be accounted for when deriving cosmological parameters from weak lensing observations. For example, baryonic physics is less important for the most massive haloes. We also present a study of the cluster merger system Abell 2146. We make new aperture mass maps by applying the aperture mass statistic to Hubble Space Telescope data of the system, using different size apertures. These maps directly show the signal-to-noise with which lensing detects features in the system. We also develop a pipeline that can in general be applied to snapshots from computer simulations of cluster merger systems. This pipeline produces maps of lensing observables that would be measured at different times during the merger process. In particular the lensing distortion field or so-called shear field can be compared with the shear field that we have estimated from Hubble Space Telescope observations, in order to find the best description of the cluster and merger parameters of the system. Finally we develop a pipeline to measure the stacked weak lensing shear and magnification signatures of galaxy clusters. We apply this pipeline to analytic models of clusters, and conclude that the shear information gives better constraints on mass models, even though the number of sources from which the shear can be measured is lower than for the magnification. In future this can be applied to synthetic catalogues for example from the BAHAMAS simulation or to real data for example from LSST or Euclid.
Download or read book Neutrino Cosmology written by Julien Lesgourgues and published by Cambridge University Press. This book was released on 2013-02-21 with total page 391 pages. Available in PDF, EPUB and Kindle. Book excerpt: A self-contained guide to the role played by neutrinos in the Universe and how their properties influence cosmological and astrophysical observations.
Download or read book Gravitational Lensing Strong Weak and Micro written by Peter Schneider and published by Springer Science & Business Media. This book was released on 2006-12-30 with total page 565 pages. Available in PDF, EPUB and Kindle. Book excerpt: The observation, in 1919 by A.S. Eddington and collaborators, of the gra- tational de?ection of light by the Sun proved one of the many predictions of Einstein’s Theory of General Relativity: The Sun was the ?rst example of a gravitational lens. In 1936, Albert Einstein published an article in which he suggested - ing stars as gravitational lenses. A year later, Fritz Zwicky pointed out that galaxies would act as lenses much more likely than stars, and also gave a list of possible applications, as a means to determine the dark matter content of galaxies and clusters of galaxies. It was only in 1979 that the ?rst example of an extragalactic gravitational lens was provided by the observation of the distant quasar QSO 0957+0561, by D. Walsh, R.F. Carswell, and R.J. Weymann. A few years later, the ?rst lens showing images in the form of arcs was detected. The theory, observations, and applications of gravitational lensing cons- tute one of the most rapidly growing branches of astrophysics. The gravi- tional de?ection of light generated by mass concentrations along a light path producesmagni?cation,multiplicity,anddistortionofimages,anddelaysp- ton propagation from one line of sight relative to another. The huge amount of scienti?c work produced over the last decade on gravitational lensing has clearly revealed its already substantial and wide impact, and its potential for future astrophysical applications.
Download or read book Adventures in Cosmology written by David L. Goodstein and published by World Scientific. This book was released on 2012 with total page 423 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume tells the tale of cosmology as seen by some of the finest cosmologists in the world. It starts with “Galaxy Formation from Start to Finish” and ends with “Understanding Dark Energy,” having a rich variety of themes in between. Designed for non-cosmological scientists, this up-to-date collection of review articles offers a general introduction to cosmology. If you are at all curious about where we came from and where we are going, this is the book for you.
Download or read book Studies Into the Averaging Problem written by Tharake S. Wijenayake and published by . This book was released on 2016 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt: With the tremendous improvement in the precision of available astrophysical data in the recent past, it becomes increasingly important to examine some of the underlying assumptions behind the standard model of cosmology and take into consideration nonlinear and relativistic corrections which may affect it at percent precision level. Due to its mathematical rigor and fully covariant and exact nature, Zalaletdinov's macroscopic gravity (MG) is arguably one of the most promising frameworks to explore nonlinearities due to inhomogeneities in the real Universe. We study the application of MG to precision cosmology, focusing on developing a self-consistent cosmology model built on the averaging framework that adequately describes the large-scale Universe and can be used to study real data sets. We first implement an algorithmic procedure using computer algebra systems to explore new exact solutions to the MG field equations. After validating the process with an existing isotropic solution, we derive a new homogeneous, anisotropic and exact solution. Next, we use the simplest (and currently only) solvable homogeneous and isotropic model of MG and obtain an observable function for cosmological expansion using some reasonable assumptions on light propagation. We find that the principal modification to the angular diameter distance is through the change in the expansion history. We then linearize the MG field equations and derive a framework that contains large-scale structure, but the small scale inhomogeneities have been smoothed out and encapsulated into an additional cosmological parameter representing the averaging effect. We derive an expression for the evolution of the density contrast and peculiar velocities and integrate them to study the growth rate of large-scale structure. We find that increasing the magnitude of the averaging term leads to enhanced growth at late times. Thus, for the same matter content, the growth rate of large scale structure in the MG model is stronger than that of the standard model. Finally, we constrain the MG model using Cosmic Microwave Background temperature anisotropy data, the distance to supernovae data, the galaxy power spectrum, the weak lensing tomography shear-shear cross-correlations and the baryonic acoustic oscillations. We find that for this model the averaging density parameter is very small and does not cause any significant shift in the other cosmological parameters. However, it can lead to increased errors on some cosmological parameters such as the Hubble constant and the amplitude of the linear matter spectrum at the scale of 8h-1Mpc. Further studies are needed to explore other solutions and models of MG as well as their effects on precision cosmology.
Download or read book Forecasting and Extracting Cosmological Information from Galaxy Cluster Peculiar Velocities written by Alan Campbell Peel and published by . This book was released on 2003 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt:
