Constraining Cosmological Models with Cosmic Microwave Background Fluctuations from the Late Universe
Author: Tommaso Giannantonio
Publisher:
Published: 2008
Total Pages:
ISBN-13:
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Constraining Cosmological Parameters with Gravitational Lensing of the Cosmic Microwave Background
Author: Gabrielle Simard
Publisher:
Published: 2018
Total Pages:
ISBN-13:
DOWNLOAD EBOOK"The cosmic microwave background (CMB) anisotropies are a direct probe of early Universe physics. They also carry information about the late Universe through different secondary effects, including gravitational lensing. Propagating away from the last scattering surface, the primary CMB photons are deflected by the intervening large-scale structure, creating slight distortions in the CMB radiation temperature and polarization patterns that can be detected statistically. In this thesis, we present constraints on the parameters describing our Universe on cosmological scales obtained with the use of CMB gravitational lensing measurements. We begin with a description of the current cosmological model and follow with a review of gravitational lensing effects on the CMB observables.We then present bounds on cosmological parameters set by the lensing power spectrum estimated from a combined SPT+Planck CMB temperature map on the SPT-SZ 2500 square-degrees patch of sky.Adding lensing information to primary CMB data helps tightening constraints on cosmological parameters affecting late-time growth, such as the matter fluctuation amplitude today, the spatial curvature and the sum of neutrino masses.Measurements of the CMB polarization sourced in the early Universe are hindered by the additional polarization created by the gravitational lensing deflections; this contaminating lensing signal can be estimated and removed. We discuss projected constraints on the scale-dependence of the primordial CMB polarization signal assuming that the lensing induced contamination can be subtracted through different scenarios." --
Constraining the Thermal History of the Universe with the Cosmic Microwave Background
Author: Silvia Galli
Publisher:
Published: 2011
Total Pages: 241
ISBN-13:
DOWNLOAD EBOOKThe excellent agreement between the Standard Model of Cosmology and the recent measurements of the Cosmic Microwave Background (CMB) permits to constrain a wide range of physical processes. In particular, in this thesis we exploit the remarkable agreement between the theoretical description of the recombination process, occurring at z~1000, and the CMB data to severely constrain phenomena that affect the evolution of the thermal history of the universe. This contributes answering some important issues still unsolved in the standard model of cosmology. We first address the problem of the nature of dark matter. An extra energy injection due to dark matter annihilation during the epoch of recombination would affect the shape of the CMB power spectra. This allows to constrain dark matter properties using the CMB. The second question regards the validity of conventional physics to describe the Universe. New fundamental theories might predict the space-time variation of fundamental 'constants'. In this thesis we test the constancy of the gravitational constant and of the fine structure constant using the CMB. The third question concerns the characteristics (and in particular, the evolution) of dark energy. The information that can be extracted from the CMB is limited, making necessary the use of complementary probes that can break degeneracies between parameters. This is the case for the evolution of the dark energy equation of state with time, that the CMB can only weakly constrain. We thus show how the observation of clusters of galaxies combined with CMB can be a powerful tool to constrain dark energy.
The Music of the Big Bang
Author: Amedeo Balbi
Publisher: Springer Science & Business Media
Published: 2008-10-16
Total Pages: 167
ISBN-13: 3540787283
DOWNLOAD EBOOKEver since its infancy, humankind has been seeking answers to some very basic and profound questions. Did the Universe begin? If it did, how old is it, and where did it come from? What is its shape? What is it made of? Fascinating myths and brilliant in- itions attempting to solve such enigmas can be found all through the history of human thought. Every culture has its own legends, itsownworldcreationtales,itsphilosophicalspeculations,itsre- gious beliefs. Modern science, however, cannot content itself with fanciful explanations, no matter how suggestive they are. No- days, our theories about the Universe, built upon rational ded- tion, have to survive the hard test of experiment and observation. Cosmology, the science which studies the origin and evo- tion of the Universe, had to overcome enormous dif?culties before it could achieve the same level of dignity as other physical dis- plines. At ?rst, it had no serious physical model and mathematical tools that could be used to address the complexity of the problems it had to face. Then, it suffered from a chronic lack of experim- tal data, which made it almost impossible to test the theoretical speculations. Given this situation, answering rigorously the many questions on the nature of the Universe seemed nothing more than a delusion. Today, however, things have changed. We live in the golden age of cosmology: an exciting moment, when, for the ?rst time, we are able to scienti?cally understand our Universe.
The Early Universe and the Cosmic Microwave Background: Theory and Observations
Author: Norma G. Sànchez
Publisher: Springer Science & Business Media
Published: 2012-12-06
Total Pages: 583
ISBN-13: 9400710585
DOWNLOAD EBOOKThe goal of the Daniel Chalonge School on Astrofundamental Physics is to contribute to a theory of the universe (and particularly of the early universe) up to the marks, and at the scientific height of, the unprecedented accuracy, existent and expected, in the observational data. The impressive development of modern cosmology during the last decades is to a large extent due to its unification with elementary particle physics and quantum field theory. The cross-section between these fields has been increasing setting up Astrofundamental Physics. The early universe is an exceptional (theoretical and experimental) laboratory in this new discipline. This NATO Advanced Study Institute provided an up dated understanding, from a fundamental physics and deep point of view, of the progress and key issues in the early universe and the cosmic microwave background: theory and observations. The genuine interplay with large scale structure formation and dark matter problem were discussed. The central focus was placed on the cosmic microwave background. Emphasis was given to the precise inter-relation between fundamental physics and cosmology in these problems, both at the theoretical and experimental/observational levels, within a deep and well defined programme which provided in addition, a careful interdisciplinarity. Special sessions were devoted to high energy cosmic rays, neutrinos in astrophysics, and high energy astrophysics. Deep understanding, clarification, synthesis, careful interdisciplinarity within a fundamental physics framework, were the main goals of the course.
CMD-variant Cosmological Models
Author: Michael Allan Kalmar Gross
Publisher:
Published: 1997
Total Pages: 556
ISBN-13:
DOWNLOAD EBOOKThe Intrinsic Bispectrum of the Cosmic Microwave Background
Author: Guido Walter Pettinari
Publisher: Springer
Published: 2016-08-23
Total Pages: 263
ISBN-13: 9783319372952
DOWNLOAD EBOOKNominated as an outstanding thesis by Professor Robert Crittenden of the Institute of Cosmology and Gravitation in Portsmouth, and winner of the Michael Penston Prize for 2014 given by the Royal Astronomical Society for the best doctoral thesis in Astronomy or Astrophysics, this work aims to shed light on one of the most important probes of the early Universe: the bispectrum of the cosmic microwave background. The CMB bispectrum is a potential window on exciting new physics, as it is sensitive to the non-Gaussian features in the primordial fluctuations, the same fluctuations that evolved into today’s planets, stars and galaxies. However, this invaluable information is potentially screened, as not all of the observed non-Gaussianity is of primordial origin. Indeed, a bispectrum arises even for perfectly Gaussian initial conditions due to non-linear dynamics, such as CMB photons scattering off free electrons and propagating in an inhomogeneous Universe. Dr. Pettinari introduces the reader to this intrinsic bispectrum in a pedagogic way, building up from the standard model of cosmology and from cosmological perturbation theory, the tool cosmologists use to unravel the history of the cosmos. In doing so, he introduces SONG, a new and efficient code for solving the second-order Einstein and Boltzmann equations. Next, he moves on to answer the crucial question: is the intrinsic bispectrum going to screen the primordial signal in the CMB? Using SONG, he computes the intrinsic bispectrum and shows how its contamination leads to a small bias in the estimates of primordial non-Gaussianity, a great news for the prospect of using CMB data to probe primordial non-Gaussianity.
Measurements of Neutrino Mass
Author: F. Ferroni
Publisher: IOS Press
Published: 2009-09-29
Total Pages: 493
ISBN-13: 1607504502
DOWNLOAD EBOOKThis volume offers a valuable insight into various aspects of the ongoing work directed at measuring neutrino mass. It took twenty years to refute the assertions of Bethe and Peierls that neutrinos were not observable, but it has since been realised that much can be learnt from these particles. The moral is, as Fiorini argues here, that the study of neutrinos was and remains demanding but rewarding. Subjects addressed in this volume include; clarifying the meaning of the Klapdor-Kleingrothaus results, probing the Majorana nature of neutrinos, observing lepton number violating effects for the first time, studying the end point of the spectrum in the search for neutrino masses and speculating whether it is possible to measure neutrino masses in cosmology. Lectures are enriched with rich historical overviews and valuable introductory material. Attention is also given to theoretical topics such as the evolution of the concept of mass in particle physics, a status report on neutrino oscillations and current discussion on neutrino masses. The reader is further reminded that neutrino masses may also have some bearing on the very origin of the matter among us, and have many deep links with other important lines of current physics research.
The Cosmic Microwave Background
Author: Ruth Durrer
Publisher:
Published: 2008
Total Pages: 401
ISBN-13: 9781107175624
DOWNLOAD EBOOKGraduate textbook examining the theory of the cosmic microwave background and its recent progress.
Cmb Anisotropies Two Years After Cobe:observations, Theory And The Future - Proceedings Of The 1994 Cwru Workshop
Author: Lawrence M Krauss
Publisher: World Scientific
Published: 1995-01-16
Total Pages: 274
ISBN-13: 9814549932
DOWNLOAD EBOOKThis volume records the latest experimental and theoretical results on anisotropies in the cosmic microwave background (CMB). The book begins with a survey article describing the main observational issues, and in which the current COBE DMR whole-sky anisotropy data — now dramatically visible above the noise — are displayed. Results and analyses by the MAX, Python, MSAM, White Dish and South Pole groups, amongst others, are included. The theoretical implications of these results for cosmological scenarios are explored. The workshop also included a discussion of how the interplay between theory and experiment can best be enhanced.
