Download or read book Improved Analysis Methods for Cosmic Microwave Background Data written by Pia Mukherjee and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Non linear Data Analysis on the Sphere written by Gregor Rossmanith and published by Springer Science & Business Media. This book was released on 2013-04-23 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work deals with the search for signatures of non-Gaussianities in the cosmic microwave background (CMB). Probing Gaussianity in the CMB addresses one of the key questions in modern cosmology because it allows us to discriminate between different models of inflation, and thus concerns a fundamental part of the standard cosmological model. The basic goal here is to adapt complementary methods stemming from the field of complexity science to CMB data analysis. Two key concepts, namely the method of surrogates and estimators for local scaling properties, are applied to CMB data analysis. All results show strong non-Gaussianities and pronounced asymmetries. The consistency of the full sky and cut sky results shows convincingly for the first time that the influence of the Galactic plane is not responsible for these deviations from Gaussianity and isotropy. The findings seriously call into question predictions of isotropic cosmologies based on the widely accepted single field slow roll inflation model.
Download or read book The Cosmic Microwave Background written by Júlio C. Fabris and published by Springer. This book was released on 2016-10-07 with total page 367 pages. Available in PDF, EPUB and Kindle. Book excerpt: The series of texts composing this book is based on the lectures presented during the II José Plínio Baptista School of Cosmology, held in Pedra Azul (Espírito Santo, Brazil) between 9 and 14 March 2014. This II JBPCosmo has been entirely devoted to the problem of understanding theoretical and observational aspects of Cosmic Background Radiation (CMB).The CMB is one of the most important phenomena in Physics and a fundamental probe of our Universe when it was only 400,000 years old. It is an extraordinary laboratory where we can learn from particle physics to cosmology; its discovery in 1965 has been a landmark event in the history of physics.The observations of the anisotropy of the cosmic microwave background radiation through the satellites COBE, WMAP and Planck provided a huge amount of data which are being analyzed in order to discover important informations regarding the composition of our universe and the process of structure formation.
Download or read book Data Analysis in Cosmology written by Vicent J. Martinez and published by Springer Science & Business Media. This book was released on 2009-03-15 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 The Blind Bayesian Approach to Cosmic Microwave Background Data Analysis written by Flavien Vansyngel and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The main topic of this thesis is the analysis of Cosmic Microwave Background (CMB) data. In particular, I present a method, Bayesian Independent component analysis (BICA), that performs both CMB component separation and CMB power spectrum inference.I begin by presenting the basics of our understanding of the CMB emission and highlight the need for a robust error modelling at the map level. Then I present the main source of errors in the CMB products, namely the foregrounds.Component separation is a crucial and delicate step in CMB data analysis. I review several methods aiming at cleaning the CMB from foregroundsThen I present BICA. The method is formulated in a blind Bayesian framework. The posterior distribution provides an inference of the CMB map and power spectrum from the observation maps. Thus, the errors on the reconstruction include the uncertainties due the presence of foregrounds in the data. By considering particular choices of prior and sampling scheme, I show how the Bayesian formulation of component separation provide a unifying framework of which previous methods are special cases.I present the results of BICA when applied on both simulated data and 2013 Planck data. This method is able to reconstruct the CMB map and power spectrum on a large fraction of the sky. The main contributions of this thesis is to provide: 1) a CMB power spectrum on a large multipole range whose errors take the presence of foregrounds into account but without assuming physical models, 2) a CMB map inference together with an error model including both noise and foregrounds residuals.
Download or read book Data Analysis of and Results from Observations of the Cosmic Microwave Background with the Cosmic Background Imager written by Jonathan LeRoy Sievers and published by . This book was released on 2004 with total page 310 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measuring Gravitational Lensing of the Cosmic Microwave Background by Large scale Structure written by Alexander van Engelen and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Lensing of the cosmic microwave background (CMB) is a rapidly-emergingcosmological probe. After describing background theory, we presentanalysis techniques developed for the measurement of lensing using CMB datafrom the South Pole Telescope. We characterize several sources of biasand systematic effects in the measurement. After presenting thereconstructed power spectrum of the CMB lensing potential from SPT data,we perform a cosmological analysis. We obtain improved constraints onseveral cosmological parameters compared to those obtained from onlyprimary CMB data, including the dark energy equation of state, thematter fluctuation amplitude today, and the spatial curvature. We thendescribe analytic techniques for computing biases in the lensingreconstruction. Finally, we discuss a related topic, the effects on theCMB from a particular type of primordial isocurvature fluctuation modethat could be large today." --
Download or read book Data Analysis of the Cosmic Microwave Background written by Frode Kristian Hansen and published by . This book was released on 2002 with total page 203 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Cosmic Microwave Background written by C.H. Lineweaver and published by Springer. This book was released on 2011-09-20 with total page 449 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of the NATO Advanced Study Institute on the Cosmological Background Radiation, Strasbourg, France, May 27-June 7, 1996
Download or read book Challenges in CMB Lensing Data Analysis and Scientific Exploitation of Current and Future CMB Polarization Experiments written by Dominic Beck and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Next-generation cosmic microwave background (CMB) measurements will further establish the field of cosmology as a high-precision science and continue opening new frontiers of fundamental physics. Cosmic-variance limited measurements not only of the CMB temperature but also its polarization down to arcminute scales will allow for precise measurements of our cosmological model, which is sensitive to the elusive physics of dark matter, dark energy and neutrinos. Furthermore, a large-scale measurement of B-mode CMB polarization permits a determination of the power of primordial gravitational waves, generated by processes potentially happening in the very early universe at energies close to the scale of the Grand Unified Theory. Entering a new sensitivity regime entails the necessity to improve our physical understanding and analysis methods of astronomical and instrumental systematics.This thesis presents within this context several analyses of potential astronomical and instrumental systematics, primarily focusing on CMB measurements related to weak gravitational lensing. The latter distorts the path of the primary CMB's photons, such that the statistical properties of the measured signal deviate from the primary signal and, hence, has to be accounted for. This thesis describes the underlying physics, analysis methods and applications to current data sets of the POLARBEAR CMB experiment in the context of CMB lensing science.This thesis shows that future high-precision measurements of CMB lensing have to account for the high complexity of this effect, primarily caused by multiple deflections within an evolving, non-linear large-scale structure distribution. Furthermore, the impact of higher-order correlations introduced by galactic foregrounds and CMB lensing when jointly analyzing CMB data sets on both large and small scales is investigated, showing the need for small-scale multi-frequency observations and foreground removal techniques to obtain an unbiased estimate of the tensor-to-scalar ratio.
Download or read book A Hunt for Cosmic Microwave Background B modes in the Sytematic Contaminants Jungle written by Josquin Errard and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents a study of selected instrumental and astrophysical systematics, which may affect the performance of new generation of future observations of the Cosmic Microwave Background (CMB) polarization. It elaborates on their impact on the science goals of those observations and discusses techniques and approaches for their removal. Its focus is on general issues typical of entire classes of experiments, but also on specific problems as encountered in the context of a CMB B-mode experiment, POLARBEAR. The main target of the CMB polarization effort undergoing currently in the field is a detection of the primordial B-modes anisotropies -- a so far undetected signature of the inflationary theories. This would have far-reaching impact on our understanding of the universe but also fundamental laws of physics. Understanding, modelling, and ultimately removal of the systematics are essential steps in any modern CMB analyste pipeline and their successful accomplishment, together with a high instrumental sensitivity, will decide of a final success of the entire effort. In this thesis I first describe optics of typical CMB experiments and introduce a parametrization of instrumental and cross-polarisation affects particularly convenient for the analysis of their impact. Second, I present a model describing the atmospheric contamination and use it to provide some insights about the atmosphere's role and its impact on performance of ground-based experiments. I also outline how it could be used further to improve control of atmospheric effects in the CMB data analysis. Then, I discuss another source of sky systematics -- the polarized astrophysical foregrounds. In this context I present on the one hand a new approach to forecasting performance of the future experiments, which accounts for the presence of the foregrounds, white on the other I propose a framework for optimizing hardware of such experiments to let them achieve better performance. This part of thesis stems from a commun work with dm. F. Stivoli and R. Stompor. I finally present one of the leading CMB polarization experiment POLARBEAR, in which I have been involved in over the course of my PhD studies. I describe its current status and performance as well as selected steps of its data analysis pipeline. In particular, I show methods to estimate some of the parameters introduced for the systematics modeling from simulated data. This work has been performed in collaboration with mernbers of the POLARBEAR team.
Download or read book Data Analysis and Scientific Exploitation of the CMB B modes Experiment POLARBEAR written by Julien Peloton and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the last two decades cosmology has been transformed from a data-starved to a data-driven, high precision science.n This transformation happened thanks to improved observational techniques, allowing to collect progressively bigger and more powerful data sets. Studies of the Cosmic Microwave Background (CMB) anisotropies have played, and continue on doing so, a particularly important and impactful role in this process. The huge data sets produced by recent CMB experiments pose new challenges for the field due to their volumes and complexity. Its successful resolution requires combining mathematical, statistical and computational methods aIl of which form a keystone of the modern CMB data analysis. In this thesis, I describe data analysis of the first data set produced by one of the most advanced, current CMB experiments, POLARBEAR and the major results it produced. The POLARBEAR experiment is a leading CMB B-mode polarization experiment aiming at detection and characterization of the so-called B-mode signature of the CMB polarization. This is one of the most exciting topics in the current CMB research, which only just has started yielding new insights onto cosmology in part thanks to the results discussed hereafter. In this thesis I describe first the modern cosmological model, focusing on the physics of the CMB, and in particular its polarization properties, and providing an overview of the past experiments and results. Subsequently, I present the POLARBEAR instrument, data analysis of its first year data set and the scientific results drawn from it, emphasizing my major contributions to the overall effort. In the last chapter, and in the context of the next generation CMB B-mode experiments, I present a more systematic study of the impact of the presence of the so-called E-to-B leakage on the performance forecasts of CMB B-modes experiments, by comparing several methods including the pure pseudospectrum method and the minimum variance quadratic estimator. In particular, I detail how the minimum variance quadratic estimator in the case of azimuthally symmetric patches can be used to estimate efficiently parameters, and I present an efficient implementation based on existing parallel algorithms for computing Spherical Harmonic Transforms.
Download or read book Development of Technologies for the Atacama Cosmology Telescope and Next Generation Cosmic Microwave Background Instruments written by Jonathan Ward and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A primary goal of modern cosmology is to obtain cosmological information and parameters from high-sensitivity measurements of the temperature and polarization of the Cosmic Microwave Background (CMB) radiation. These measurements will allow cosmologists to probe the many predictions made by the inflationary model of the Universe. To continue expanding the limits of CMB science, experimentalists need to develop novel technologies that will continue to improve our ability to observe the microwave sky. Paired with state of the art data analysis techniques, our understanding of the Universe will continue to grow now and for decades to come.The Atacama Cosmology Telescope (ACT) is a 6-meter diameter telescope located in the Andes Mountains of Northern Chile. Deployment of the Advanced ACTPol (AdvACT) receiver has vastly improved the capabilities of ACT. Next-generation detector arrays operating at 20, 40, 90, 150, and 240 GHz will provide the frequency coverage and detector count necessary to improve measurements of a wide range of cosmological parameters. Continuously rotating half-wave plates (HWPs) modulate the incoming polarized signal, resulting in a drastic suppression of the atmospheric 1/f noise that contaminates the ACT data at large angular scales. Finally, hardware and software upgrades to previous-generation ACTPol infrastructure have further improved the AdvACT instrument on the fronts of cryogenic performance, housekeeping data acquisition, assembly procedure, and site reliability. The design and deployment of AdvACT instrumentation is discussed in detail from Chapters 2-4, highlighting the key design changes and improvements over the ACTPol experiment. In addition to the instrumentation advances discussed above, data analysis and numerical modeling techniques provide the framework needed to extract the most information from the data gathered by the AdvACT experiment. Key efforts focused towards processing HWP data allows ACT to probe the inflationary gravitational wave signal that may lie in the low-frequency regime of the ACT data. Furthermore, simulations help predict the effects of various systematics on the raw data give a better understanding of what calibration strategies are needed to mitigate systematic effects. The software developed to accomplish these tasks is discussed in Chapters 5-6, along with the results obtained from the data when the code is implemented in the analysis pipeline. The technologies, instrumentation, and analysis techniques outlined in this paper and employed by the AdvACT experiment will continue to push ACT to the forefront of experimental cosmology research while also providing a template for future experimental efforts.
Download or read book The Cosmic Microwave Background written by Ruth Durrer and published by . This book was released on 2008 with total page 401 pages. Available in PDF, EPUB and Kindle. Book excerpt: Graduate textbook examining the theory of the cosmic microwave background and its recent progress.
Download or read book The Investigation Development and Testing of Novel Methods for the Statistical Characterisation of Cosmic Microwave Background Data Aimed at Isolating and Quantifying Departures from the Standard Cosmological Model And Large Scale Galaxy Clustering Data Aimed at Refining Estimates of Key Parameters Required for the Advancement of Galaxy Formation Theory written by Joanna Short and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The thesis concerns the statistical characterisation of large scale properties of the Universe. Two complementary data sets are considered: all-sky maps of the cosmic microwave background (CMB) temperature fluctuations from the Wilkinson Microwave Anisotropy Probe (WMAP); and large area maps of galaxies detected through the sub-millimetre electromagnetic emission using the Herschel Space Observatory. The standard model predicts the distribution of temperature fluctuations in the CMB to be Gaussian, homogeneous and isotropic. Since they could deviate from the standard model in many different ways, a number of complementary descriptors are required. All-sky maps of the CMB are often decomposed into spherical harmonic modes. Any modes aligned with the Galactic plane are particularly interesting because anomalous behaviour in them could indicate errors in the subtraction of Galactic foreground. Here a simple statistical analysis of these modes is tested and shown to be a useful diagnostic of possible foreground subtraction systematics. In addition, two methods for characterizing large-scale anisotropy in all sky CMB maps are discussed. They are tested against simulated anisotropic cosmologies and both show promise as effective diagnostic tools. The second part concerns analytical models of the correlation function for the distribution of galaxies. The 'Halo' model is comprehensive, but it is also rather complex. We promote a simpler alternative based on fitting functions found from numerical simulations. Both models compare well to the observational data, showing that the fitting function method can be a quick and easy option. Also, we show that a 'key' Halo model assumption, intra-halo correlations, is not required to produce a good fit. We summarise by discussing the different approximations used in the current galaxy clustering models, the limits of the currently available data and future areas of development.
Download or read book Data Analysis Techniques Useful for the Detection of B mode Polarisation of the Cosmic Microwave Background written by Christopher Wallis and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dechiphering Precision Cosmic Microwave Background Data written by Marius Millea and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis centers around work which was performed in the lead up to and during analysis of high resolution cosmic microwave background (CMB) data coming from the South Pole Telescope and from the Planck satellite. Analysis of such data necessitates modeling of extra-galactic foregrounds, and here we develop a model for these foregrounds for use with current data. This model is shown to be both necessary and sufficient for unbiased estimation of cosmological parameters. Additionally, we develop a novel method for using auxiliary data in the form of galaxy number counts to put priors on certain components of this model. Finally, we perform an analysis of CMB data, taking into account these extra-galactic foregrounds, to calculate new constraints on hypothetical particles like axions or axion-like particles. We find new data from Planck and from measurements of primordial deuterium newly rule out some theoretically interesting regions of parameter space. In addition, we show that in a more speculative scenario which includes the presence of both axions and other dark radiation, some of these regions are again allowed and could explain hints of high primordial helium fraction, or could allow one or two thermalized sterile neutrinos to exist.
