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Author: Muhammad Omer Farooq
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
The expansion rate of the Universe changes with time, initially slowing (decelerating) when the universe was matter dominated, because of the mutual gravitational attraction of all the matter in it, and more recently speeding up (accelerating). A number of cosmological observations now strongly support the idea that the Universe is spatially flat (provided the dark energy density is at least approximately time independent) and is currently undergoing an accelerated cosmological expansion. A majority of cosmologists consider "dark energy" to be the cause of this observed accelerated cosmological expansion. The "standard" model of cosmology is the spatially-flat ACDM model. Although most predictions of the ACDM model are reasonably consistent with measurements, the ACDM model has some curious features. To overcome these difficulties, different Dark Energy models have been proposed. Two of these models, the XCDM parametrization and the slow rolling scalar field model [phi]CDM, along with "standard" ACDM, with the generalization of XCDM and [phi]CDM in non-flat spatial geometries are considered here and observational data are used to constrain their parameter sets. In this thesis, we start with a overview of the general theory of relativity, Friedmann's equations, and distance measures in cosmology. In the following chapters we explain how we can constrain the three above mentioned cosmological models using three data sets: measurements of the Hubble parameter H(z), Supernova (SN) apparent magnitudes, and the baryonic acoustic oscillations (BAO) peak length scale, as functions of redshift z. We then discuss constraints on the deceleration-acceleration transition redshift z[subscript]d[subscript]a using unbinned and binned H(z) data. Finally, we incorporate the spatial curvature in the XCDM and [phi]CDM model and determine observational constraints on the parameters of these expanded models.
Author: Muhammad Omer Farooq
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
The expansion rate of the Universe changes with time, initially slowing (decelerating) when the universe was matter dominated, because of the mutual gravitational attraction of all the matter in it, and more recently speeding up (accelerating). A number of cosmological observations now strongly support the idea that the Universe is spatially flat (provided the dark energy density is at least approximately time independent) and is currently undergoing an accelerated cosmological expansion. A majority of cosmologists consider "dark energy" to be the cause of this observed accelerated cosmological expansion. The "standard" model of cosmology is the spatially-flat ACDM model. Although most predictions of the ACDM model are reasonably consistent with measurements, the ACDM model has some curious features. To overcome these difficulties, different Dark Energy models have been proposed. Two of these models, the XCDM parametrization and the slow rolling scalar field model [phi]CDM, along with "standard" ACDM, with the generalization of XCDM and [phi]CDM in non-flat spatial geometries are considered here and observational data are used to constrain their parameter sets. In this thesis, we start with a overview of the general theory of relativity, Friedmann's equations, and distance measures in cosmology. In the following chapters we explain how we can constrain the three above mentioned cosmological models using three data sets: measurements of the Hubble parameter H(z), Supernova (SN) apparent magnitudes, and the baryonic acoustic oscillations (BAO) peak length scale, as functions of redshift z. We then discuss constraints on the deceleration-acceleration transition redshift z[subscript]d[subscript]a using unbinned and binned H(z) data. Finally, we incorporate the spatial curvature in the XCDM and [phi]CDM model and determine observational constraints on the parameters of these expanded models.
Author: Luca Amendola
Publisher: Cambridge University Press
ISBN: 0521516005
Category : Science
Languages : en
Pages : 507
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Book Description
Introducing the theoretical ideas, observational methods and results in dark energy, this textbook is a thorough introduction to dark energy for graduate courses.
Author: Georg Wolschin
Publisher: Springer
ISBN: 364210598X
Category : Science
Languages : en
Pages : 188
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Book Description
The lectures that four authors present in this volume investigate core topics related to the accelerated expansion of the Universe. Accelerated expansion occured in the ?36 very early Universe – an exponential expansion in the in ationary period 10 s after the Big Bang. This well-established theoretical concept had rst been p- posed in 1980 by Alan Guth to account for the homogeneity and isotropy of the observable universe, and simultaneously by Alexei Starobinski, and has since then been developed by many authors in great theoretical detail. An accelerated expansion of the late Universe at redshifts z
Author: Remo Ruffini
Publisher: World Scientific
ISBN: 9811269785
Category : Science
Languages : en
Pages : 4880
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Book Description
The proceedings of MG16 give a broad view of all aspects of gravitational physics and astrophysics, from mathematical issues to recent observations and experiments. The scientific program of the meeting included 46 plenary presentations, 3 public lectures, 5 round tables and 81 parallel sessions arranged during the intense six-day online meeting. All talks were recorded and are available on the ICRANet YouTube channel at the following link: www.icranet.org/video_mg16.These proceedings are a representative sample of the very many contributions made at the meeting. They contain 383 papers, among which 14 come from the plenary sessions.The material represented in these proceedings cover the following topics: accretion, active galactic nuclei, alternative theories of gravity, black holes (theory, observations and experiments), binaries, boson stars, cosmic microwave background, cosmic strings, dark energy and large scale structure, dark matter, education, exact solutions, early universe, fundamental interactions and stellar evolution, fast transients, gravitational waves, high energy physics, history of relativity, neutron stars, precision tests, quantum gravity, strong fields, and white dwarf; all of them represented by a large number of contributions.The online e-proceedings are published in an open access format.
Author: Kazuharu Bamba
Publisher: MDPI
ISBN: 303921764X
Category : Science
Languages : en
Pages : 236
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Book Description
Various cosmological observations support not only cosmological inflation in the early universe, which is also known as exponential cosmic expansion, but also that the expansion of the late-time universe is accelerating. To explain this phenomenon, the existence of dark energy is proposed. In addition, according to the rotation curve of galaxies, the existence of dark matter, which does not shine, is also suggested. If primordial gravitational waves are detected in the future, the mechanism for realizing inflation can be revealed. Moreover, there exist two main candidates for dark matter. The first is a new particle, the existence of which is predicted in particle physics. The second is an astrophysical object which is not found by electromagnetic waves. Furthermore, there are two representative approaches to account for the accelerated expansion of the current universe. One is to assume the unknown dark energy in general relativity. The other is to extend the gravity theory to large scales. Investigation of the origins of inflation, dark matter, and dark energy is one of the most fundamental problems in modern physics and cosmology. The purpose of this book is to explore the physics and cosmology of inflation, dark matter, and dark energy.
Author: Elise Jennings
Publisher: Springer Science & Business Media
ISBN: 3642293395
Category : Science
Languages : en
Pages : 117
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Book Description
A major outstanding problem in physics is understanding the nature of the dark energy that is driving the accelerating expansion of the Universe. This thesis makes a significant contribution by demonstrating, for the first time, using state-of-the-art computer simulations, that the interpretation of future galaxy survey measurements is far more subtle than is widely assumed, and that a major revision to our models of these effects is urgently needed. The work contained in the thesis was used by the WiggleZ dark energy survey to measure the growth rate of cosmic structure in 2011 and had a direct impact on the design of the surveys to be conducted by the European Space Agency's Euclid mission, a 650 million euro project to measure dark energy.
Author: Gianfranco Bertone
Publisher: Cambridge University Press
ISBN: 0521763681
Category : Science
Languages : en
Pages : 763
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Book Description
Describes the dark matter problem in particle physics, astrophysics and cosmology for graduate students and researchers.
Author: Andrew R. Liddle
Publisher: Cambridge University Press
ISBN: 9780521575980
Category : Science
Languages : en
Pages : 420
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Book Description
A thorough and up-to-date graduate textbook on the most promising theory of the universe - inflationary cosmology.
Author: C.H. Lineweaver
Publisher: Springer
ISBN: 9789401065122
Category : Science
Languages : en
Pages : 449
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Book Description
Proceedings of the NATO Advanced Study Institute on the Cosmological Background Radiation, Strasbourg, France, May 27-June 7, 1996
Author: I︠A︡kov Borisovich Zelʹdovich
Publisher: University of Chicago Press
ISBN: 9780226979571
Category : Science
Languages : en
Pages : 760
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Book Description
Though the kinematics of the evolving universe became known decades ago, research into the physics of processes occurring in the expanding universe received a reliable observational and theoretical basis only in more recent years. These achievements have led in turn to the emergence of new problems, on which an unusually active assault has begun. This second volume of Relativistic Astrophysics provides a remarkably complete picture of the present state of cosmology. It is a synthesis of the theoretical foundations of contemporary cosmology, which are derived from work in relativity, plasma theory, thermodynamics, hydrodynamics, and particle physics. It presents the theoretical work that explains, describes, and predicts the nature of the universe, the physical process that occur in it, the formation of galaxies, the synthesis of the light elements, and the cosmological singularity and the theory of gravitation. This book, long and eagerly awaited, is essential for everyone whose work is related to cosmology and astrophysics.
