Download or read book Weak Lensing Techniques on the Curved Sky written by Zoe M. Vallis and published by . This book was released on 2019 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: Future weak lensing surveys will cover larger areas of the sky that necessitate analysis on the curved sky geometry instead of projections to the plane. This thesis focuses on reconstructing convergence maps from cosmic shear on the curved sky geometry. These convergence maps are useful tools for cosmological analysis, including probing non-Gaussian properties. The first chapter focuses on evaluating the performance of different methods of projecting simulated shear data from the curved sky to the plane, to subsequently undergo Kaiser-Squires reconstruction and analysis, and drawing comparisons to reconstruction and analysis directly on the sphere, using peak counts and Minkowski Functionals as the statistics selected for comparison. It is found that projections to the plane are only effective for small areas and it is preferable to perform analysis directly on the sphere when possible. Under ideal circumstances, peak counts derived from data projected using the sine and orthographic projections are most accurate to the spherical case. For the Minkowski Functionals there are significant differences that persist even when attempting to mitigate the projection effects. While certain projections allow reasonable approximations of the spherical sky geometry, it is impractical to use such projections on data covering large areas of the sky and performing analysis on the spherical setting is preferable. The second and third chapters focus on the separation of E-modes and B-modes through wavelet pure mode estimators on the sphere, which cancel mode mixing caused by masking of the shear data. The aim is to remove ambiguous modes to produce pure E-B modes, providing greater accuracy for studying cosmology from them. An evaluation of the accuracy of this method is performed using simulated data to compare the Kaiser-Squires, harmonic pure estimator and wavelet pure estimator methods. This finds a significant improvement in the accuracy of recovering simulated E-modes and B-modes when using the wavelet pure estimator, over the Kaiser-Squires method and harmonic pure estimator. This wavelet pure estimator method is applied to DES Y1 data and statistics, including the Minkowski Functionals, are derived and discussed. The wavelet pure estimator successfully reconstructs the E-mode and B-mode maps accurate to previous studies of the data. The Minkowski Functionals of the E-modes and B-modes display distinct differences to the analytic form for a 2D Gaussian random field. A new problem is discovered in the apodisation of the data near the mask boundary, and a potential solution is attempted through identifying and removing apodised pixels with a new mask.
Download or read book CALCLENS Weak Lensing Simulations for Large area Sky Surveys and Second order Effects in Cosmic Shear Power Spectra written by Matthew Rand Becker and published by . This book was released on 2013 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt: I present a new algorithm, CALCLENS, for efficiently computing weak gravitational lensing shear signals from large N-body light cone simulations over a curved sky. This new algorithm properly accounts for the sky curvature and boundary conditions, is able to produce redshift- dependent shear signals including corrections to the Born approximation by using multiple- plane ray tracing, and properly computes the lensed images of source galaxies in the light cone. The key feature of this algorithm is a new, computationally efficient Poisson solver for the sphere that combines spherical harmonic transform and multigrid methods. As a result, large areas of sky (~10,000 square degrees) can be ray traced efficiently at high-resolution using only a few hundred cores. Using this new algorithm and curved-sky calculations that only use a slower but more accurate spherical harmonic transform Poisson solver, I study the convergence, shear E-mode, shear B-mode and rotation mode power spectra. Employing full-sky E/B-mode decompositions, I confirm that the numerically computed shear B-mode and rotation mode power spectra are equal at high accuracy ( ≲ 1%) as expected from perturbation theory up to second order. Coupled with realistic galaxy populations placed in large N-body light cone simulations, this new algorithm is ideally suited for the construction of synthetic weak lensing shear catalogs to be used to test for systematic effects in data analysis procedures for upcoming large-area sky surveys. The implementation presented in this work, written in C and employing widely available software libraries to maintain portability, is publicly available at http://code.google.com/p/calclens.
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 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 The Extragalactic Distance Scale written by Space Telescope Science Institute (U.S.). Symposium and published by Cambridge University Press. This book was released on 1997-06-28 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the hottest debates in astronomy and cosmology today concerns the value of the Hubble constant. This constant is of paramount importance since it fixes the size and age of the Universe. At a symposium at the Space Telescope Science Institute, experts from around the world presented the latest results from a plethora of techniques for determining the Hubble constant. The value has always been controversial, but at this meeting experts' results agreed for the first time to within about 20%. Based on the meeting, this book presents twenty-three specially written review articles. They provide a comprehensive account of the Hubble-constant debate with the latest results from gravitational lensing, supernovae and novae, the Tully-Fisher relation, the Sunyaev-Zeldovich effect, globular clusters, planetary nebulae, light echoes, and the Hubble Space Telescope Key Project. This timely volume provides a standard reference for graduate students and researchers in astronomy and cosmology.
Download or read book Large scale Peculiar Motions Matter In Motion written by Gary A Wegner and published by World Scientific. This book was released on 2021-11-24 with total page 379 pages. Available in PDF, EPUB and Kindle. Book excerpt: All matter, including galaxy clusters, galaxies, and their constituents follow orbits and flows driven by the net attraction of near and distant masses. The book presents the development of studies of peculiar motions along with discoveries in large-scale structure, the cosmic microwave background, baryonic oscillations, gravity waves, and their relation to current work on gravitation and dark matter.The results of peculiar motion measurements in the late 20th century are described as they were used to search for the dipole of the galaxy motions, a determination of cosmic density, and to compare with the cosmic microwave dipole, which led to the discovery of galactic flows and the Great Attractor. Newer detailed measurements from surveys in the 21st century have helped resolve the nature of these structures. Some prospects for future investigations are discussed.
Download or read book The Science of Interstellar written by Kip Thorne and published by W. W. Norton & Company. This book was released on 2014-11-07 with total page 560 pages. Available in PDF, EPUB and Kindle. Book excerpt: A journey through the otherworldly science behind Christopher Nolan’s award-winning film, Interstellar, from executive producer and Nobel Prize-winning physicist Kip Thorne. Interstellar, from acclaimed filmmaker Christopher Nolan, takes us on a fantastic voyage far beyond our solar system. Yet in The Science of Interstellar, Kip Thorne, the Nobel prize-winning physicist who assisted Nolan on the scientific aspects of Interstellar, shows us that the movie’s jaw-dropping events and stunning, never-before-attempted visuals are grounded in real science. Thorne shares his experiences working as the science adviser on the film and then moves on to the science itself. In chapters on wormholes, black holes, interstellar travel, and much more, Thorne’s scientific insights—many of them triggered during the actual scripting and shooting of Interstellar—describe the physical laws that govern our universe and the truly astounding phenomena that those laws make possible. Interstellar and all related characters and elements are trademarks of and © Warner Bros. Entertainment Inc. (s14).
Download or read book Astronomical Image and Data Analysis written by J.-L. Starck and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt: Using information and scale as central themes, this comprehensive survey explains how to handle real problems in astronomical data analysis through a modern arsenal of powerful techniques. The coverage includes chapters or appendices on: detection and filtering; image compression; multichannel, multiscale, and catalog data analytical methods; wavelets transforms, Picard iteration, and software tools.
Download or read book Principles of Gravitational Lensing written by Arthur B. Congdon and published by Springer. This book was released on 2018-12-01 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt: This textbook provides an introduction to gravitational lensing, which has become an invaluable tool in modern astrophysics, with applications that range from finding planets orbiting distant stars to understanding how dark matter and dark energy conspired to form the cosmic structures we see today. Principles of Gravitational Lensing begins with Einstein’s prediction that gravity bends light, and shows how that fundamental idea has spawned a rich field of study over the past century. The gravitational deflection of light was first detected by Eddington during a solar eclipse in May 1919, launching Einstein and his theory of relativity into public view. Yet the possibility of using the phenomenon to unlock mysteries of the Universe seemed remote, given the technology of the day. Theoretical work was carried out sporadically over the next six decades, but only with the discovery of the system Q0957+561 in 1979 was gravitational lensing transformed from a curiosity of general relativity into a practical observational tool. This book describes how the three subfields known as strong lensing, weak lensing, and microlensing have grown independently but become increasingly intertwined. Drawing on their research experience, Congdon and Keeton begin with the basic physics of light bending, then present the mathematical foundations of gravitational lensing, building up to current research topics in a clear and systematic way. Relevant background material from physics and mathematics is included, making the book self-contained. The derivations and explanations are supplemented by exercises designed to help students master the theoretical concepts as well as the methods that drive current research. An extensive bibliography guides those wishing to delve more deeply into particular areas of interest. Principles of Gravitational Lensing is ideal for advanced students and seasoned researchers looking to penetrate this thriving subject and even contribute research of their own.
Download or read book The Sky Atlas written by Edward Brooke-Hitching and published by Simon and Schuster. This book was released on 2019-10-17 with total page 417 pages. Available in PDF, EPUB and Kindle. Book excerpt: After the enormous international success of The Phantom Atlas and The Golden Atlas, Edward Brooke-Hitching's stunning new book unveils some of the most beautiful maps and charts ever created during mankind's quest to map the skies above us. This richly illustrated treasury showcases the finest examples of celestial cartography - a glorious genre of map-making often overlooked by modern map books - as well as medieval manuscripts, masterpiece paintings, ancient star catalogues, antique instruments and other appealing curiosities. This is the sky as it has never been presented before: the realm of stars and planets, but also of gods, devils, weather wizards, flying sailors, medieval aliens, mythological animals and rampaging spirits. The reader is taken on a tour of star-obsessed cultures around the world, learning about Tibetan sky burials, star-covered Inuit dancing coats, Mongolian astral prophets and Sir William Herschel's 1781 discovery of Uranus, the first planet to be found since antiquity. Even stranger are the forgotten stories from European history, like the English belief of the Middle Ages in ships that sailed a sea above the clouds, 16th-century German UFO sightings and the Edwardian aristocrat who mistakenly mapped alien-made canals on the surface of Mars. As the intricacies of our universe are today being revealed with unprecedented clarity, there has never been a better time for a highly readable book as beautiful as the night sky to contextualise the scale of these achievements for the general reader.
Download or read book Formation of Structure in the Universe written by Avishai Dekel and published by Cambridge University Press. This book was released on 1999-04-15 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt: This advanced textbook provides an up-to-date and comprehensive introduction to the very active field of structure formation in cosmology. It is written by eleven world-leading authorities. Written in a clear and pedagogical style appropriate for graduate students in astronomy and physics, this textbook introduces the reader to a wide range of exciting topics in contemporary cosmology: from recent advances in redshift surveys, to the latest models in gravitational lensing and cosmological simulations. The authors are all world-renowned experts both for their research and teaching skills. In the fast-moving field of structure formation, this book provides advanced undergraduate and graduate students with a welcome textbook which unites the latest theory and observations.
Download or read book Questions of Modern Cosmology written by Mauro D'Onofrio and published by Springer Science & Business Media. This book was released on 2009-07-09 with total page 552 pages. Available in PDF, EPUB and Kindle. Book excerpt: Are we living in the "golden age" of cosmology? Are we close to understanding the nature of the unknown ingredients of the currently most accepted cosmological model and the physics of the early Universe? Or are we instead approaching a paradigm shift? What is dark matter and does it exist? How is it distributed around galaxies and clusters? Is the scientific community open to alternative ideas that may prompt a new scientific revolution - as the Copernican revolution did in Galileo's time? Do other types of supernovae exist that can be of interest for cosmology? Why have quasars never been effectively used as standard candles? Can you tell us about the scientific adventure of COBE? How does the extraction of the Cosmic Microwave Background anisotropy depend on the subtraction of the various astrophysical foregrounds? These, among many others, are the astrophysical, philosophical and sociological questions surrounding modern cosmology and the scientific community that Mauro D'Onofrio and Carlo Burigana pose to some of the most prominent cosmologists of our time. Triggered by these questions and in the spirit of Galileo's book "Dialogue Concerning the Two Chief World Systems" the roughly 40 interview partners reply in the form of essays, with a critical frankness not normally found in reviews, monographs or textbooks.
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 Merging Processes in Galaxy Clusters written by L. Feretti and published by Springer Science & Business Media. This book was released on 2006-04-18 with total page 329 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mergers are the mechanisms by which galaxy clusters are assembled through the hierarchical growth of smaller clusters and groups. Major cluster mergers are the most energetic events in the Universe since the Big Bang. Many of the observed properties of clusters depend on the physics of the merging process. These include substructure, shock, intra cluster plasma temperature and entropy structure, mixing of heavy elements within the intra cluster medium, acceleration of high-energy particles, formation of radio halos and the effects on the galaxy radio emission. This book reviews our current understanding of cluster merging from an observational and theoretical perspective, and is appropriate for both graduate students and researchers in the field.
Download or read book Astronomy and Astrophysics in the New Millennium written by National Research Council and published by National Academies Press. This book was released on 2002-02-07 with total page 401 pages. Available in PDF, EPUB and Kindle. Book excerpt: In preparing the report, Astronomy and Astrophysics in the New Millenium , the AASC made use of a series of panel reports that address various aspects of ground- and space-based astronomy and astrophysics. These reports provide in-depth technical detail. Astronomy and Astrophysics in the New Millenium: An Overview summarizes the science goals and recommended initiatives in a short, richly illustrated, non-technical booklet.
Download or read book The Application of Weak Lensing written by Yong-Seon Song and published by . This book was released on 2004 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Introduction to Cosmology written by Barbara Ryden and published by Cambridge University Press. This book was released on 2017 with total page 277 pages. Available in PDF, EPUB and Kindle. Book excerpt: A substantial update of this award-winning and highly regarded cosmology textbook, for advanced undergraduates in physics and astronomy.
