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Author: Jonathan Andrew Pearson
Publisher:
ISBN: 9783319012117
Category :
Languages : en
Pages : 222
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Book Description
When recent observational data and the GR+FRW+CDM model are combined we obtain the result that the Universe is accelerating, where the acceleration is due to some not-yet-understood "dark sector". There has been a considerable number of theoretical models constructed in an attempt to provide a description of the dark sector: dark energy and modified gravity theories. The proliferation of modified gravity and dark energy models has brought to light the need to construct a "generic" way to parameterize perturbations in the dark sector. In this thesis we discuss our new way of approaching this problem. We write down an effective action for linearized perturbations to the gravitational field equations for a given field content and use it to compute generalized gravitational field equations for linearized perturbations. Our approach is inspired by that taken in particle physics, where the most general modifications to the standard model are written down for a given field content that is compatible with some assumed symmetry (which we take to be isotropy of the background spatial sections). After applying the formalism we obtain equations of state for dark sector perturbations, where the number of free parameters for wide classes of theories are identified.
Author: Jonathan Andrew Pearson
Publisher:
ISBN: 9783319012117
Category :
Languages : en
Pages : 222
Get Book Here
Book Description
When recent observational data and the GR+FRW+CDM model are combined we obtain the result that the Universe is accelerating, where the acceleration is due to some not-yet-understood "dark sector". There has been a considerable number of theoretical models constructed in an attempt to provide a description of the dark sector: dark energy and modified gravity theories. The proliferation of modified gravity and dark energy models has brought to light the need to construct a "generic" way to parameterize perturbations in the dark sector. In this thesis we discuss our new way of approaching this problem. We write down an effective action for linearized perturbations to the gravitational field equations for a given field content and use it to compute generalized gravitational field equations for linearized perturbations. Our approach is inspired by that taken in particle physics, where the most general modifications to the standard model are written down for a given field content that is compatible with some assumed symmetry (which we take to be isotropy of the background spatial sections). After applying the formalism we obtain equations of state for dark sector perturbations, where the number of free parameters for wide classes of theories are identified.
Author: Jonathan Pearson
Publisher: Springer Science & Business Media
ISBN: 331901210X
Category : Science
Languages : en
Pages : 213
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Book Description
When predictions of Einstein's theory of General Relativity are compared against observations of our Universe, a huge inconsistency is found. The most popular fix for this inconsistency is to "invent" around 94% of the content of the universe: dark matter and dark energy. The dark energy is some exotic substance responsible for the apparent observed acceleration of the Universe. Another fix is to modify the theory of gravity: it is entirely plausible that Einstein's theory of General Relativity breaks down on cosmological scales, just as Newton's theory of gravity breaks down in the extreme gravitational field of the Sun. There are many alternative theories of gravity, each with the aim of describing observations of our Universe where General Relativity fails. Whether it is dark energy or some modified theory of gravity, it is clear that there is some "dark sector" in the Universe. In this thesis the author constructs a unifying framework for understanding the observational impact of general classes of dark sector theories, by formulating equations of state for the dark sector perturbations.
Author: Baojiu Li
Publisher: World Scientific
ISBN: 9813274018
Category : Science
Languages : en
Pages : 324
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Book Description
Modified gravity theories have been a main focus of theoretical cosmology research in the past decade or so, and have been quickly developing into a mature research field that attracts attention, interest and effort from both theoretical and observational cosmologists. To be prepared for fully exploiting the future observational data, and to provide a guidance for people who are new to this field, it is useful to have a comprehensive review to summarise the current state of knowledge and to foresee the future developments.This book presents expert reviews on different topics in the field, which are then coordinated and organised in a self-consistent and self-contained manner. It is suitable for graduate students and researchers interested in the frontier research of gravity theories.
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: Gianluca Calcagni
Publisher: Springer
ISBN: 3319411276
Category : Science
Languages : en
Pages : 854
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Book Description
This comprehensive textbook is devoted to classical and quantum cosmology, with particular emphasis on modern approaches to quantum gravity and string theory and on their observational imprint. It covers major challenges in theoretical physics such as the big bang and the cosmological constant problem. An extensive review of standard cosmology, the cosmic microwave background, inflation and dark energy sets the scene for the phenomenological application of all the main quantum-gravity and string-theory models of cosmology. Born of the author's teaching experience and commitment to bridging the gap between cosmologists and theoreticians working beyond the established laws of particle physics and general relativity, this is a unique text where quantum-gravity approaches and string theory are treated on an equal footing. As well as introducing cosmology to undergraduate and graduate students with its pedagogical presentation and the help of 45 solved exercises, this book, which includes an ambitious bibliography of about 3500 items, will serve as a valuable reference for lecturers and researchers.
Author: Abraao Jesse Capistrano
Publisher: BoD – Books on Demand
ISBN: 9535132091
Category : Science
Languages : en
Pages : 226
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Book Description
The modern cosmology has been turned into an outstanding field of active research through the years. Today, we have more scientific data in modern cosmology than we could get rid of it, which makes the present days an exciting era for scientific knowledge. "Trends in Modern Cosmology" invites the reader to tackle the big questions of the universe from cultural aspects of cosmology and its influence on arts, philosophy, and politics to more specialized technical advances in the field as the physics of dark sector, black holes, galaxies, large structure formation, and particles. In fact, it reveals our endless searching for the better understanding of the universe as a legacy of knowledge for next generations.
Author: Rennan Barkana
Publisher: World Scientific
ISBN: 9814656216
Category : Science
Languages : en
Pages : 1402
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Book Description
The Encyclopedia of Cosmology is a new and exciting project which will be a major, long-lasting, seminal reference (a set of four major volumes) at the graduate student level, laid out by the most prominent, respected researchers in the general field of Cosmology. These volumes will be a comprehensive review of the most important concepts and current status in the field of Cosmology of the Universe, covering both theory and observation.One of the most exciting parts of the encyclopedia is that it will exist in both print and, more importantly, electronic forms, perhaps even with some level of interactivity with material such as expanded explanations, movie clips, dynamic pictures, examples of on-line computation, etc. The electronic version will also reflect constant updates of the material. It will be a truly unique publication, unlike anything any of us have seen or known of in existence today.This comprehensive encyclopedia is edited by Dr. Giovanni Fazio from Harvard Smithsonian Center for Astrophysics, with an advisory board comprised of renowned scientists: Lars Hernquist and Abraham Loeb (Harvard Smithsonian Center for Astrophysics), and Christopher McKee (UC Berkeley). Each volume is authored/edited by a specialist in the area: Galaxy Formation and Evolution written by Rennan Barkana (Tel Aviv University), Numerical Simulations in Cosmology edited by Kentaro Nagamine (Osaka University / University of Nevada), Dark Energy written by Shinji Tsujikawa (Tokyo University of Science), and Dark Matter written by Jihn Kim (Seoul National University).
Author: Eleftherios Papantonopoulos
Publisher: Springer
ISBN: 331910070X
Category : Science
Languages : en
Pages : 435
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Book Description
In the last few years modified gravity theories have been proposed as extensions of Einstein's theory of gravity. Their main motivation is to explain the latest cosmological and astrophysical data on dark energy and dark matter. The study of general relativity at small scales has already produced important results (cf e.g. LNP 863 Quantum Gravity and Quantum Cosmology) while its study at large scales is challenging because recent and upcoming observational results will provide important information on the validity of these modified theories. In this volume, various aspects of modified gravity at large scales will be discussed: high-curvature gravity theories; general scalar-tensor theories; Galileon theories and their cosmological applications; F(R) gravity theories; massive, new massive and topologically massive gravity; Chern-Simons modifications of general relativity (including holographic variants) and higher-spin gravity theories, to name but a few of the most important recent developments. Edited and authored by leading researchers in the field and cast into the form of a multi-author textbook at postgraduate level, this volume will be of benefit to all postgraduate students and newcomers from neighboring disciplines wishing to find a comprehensive guide for their future research.
Author: Matts Roos
Publisher: John Wiley & Sons
ISBN: 1118923286
Category : Science
Languages : en
Pages : 288
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Book Description
The Fourth Edition of Introduction to Cosmology provides a concise, authoritative study of cosmology at an introductory level. Starting from elementary principles and the early history of cosmology, the text carefully guides the student on to curved spacetimes, special and general relativity, gravitational lensing, the thermal history of the Universe, and cosmological models, including extended gravity models, black holes and Hawking's recent conjectures on the not-so-black holes. Introduction to Cosmology, Fourth Edition includes: New theoretical approaches and in-depth material on observational astrophysics and expanded sections on astrophysical phenomena Illustrations throughout and comprehensive references with problems at the end of each chapter and a rich index at the end of the book Latest observational results from WMAP9, ACT, and Planck, and all cosmological parameters have been brought up to date. This text is invaluable for undergraduate students in physics and astrophysics taking a first course in cosmology. Extensively revised, this latest edition extends the chapter on cosmic inflation to the recent schism on eternal inflation and multiverses. Dark matter is discussed on galaxy and cluster scales, and dark matter candidates are presented, some requiring a five-dimensional universe and several representing various types of exotica. In the context of cosmic structures the cold dark matter paradigm is described. Dark energy models include the cosmological constant, quintessence and other single field models, f(R) models and models requiring extra dimensions.
Author: Baojiu Li
Publisher: World Scientific Publishing Company
ISBN: 9789813273993
Category : Science
Languages : en
Pages : 0
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Book Description
Gravity beyond general relativity / Kazuya Koyama -- Parametrizations for tests of gravity / Lucas Lombriser -- Simulation techniques / Claudio Llinares -- Approximation methods in modified gravity models / Baojiu Li -- Large-scale structure probes of modified gravity / Catherine Heymans and Gong-Bo Zhao -- Tests of gravity with galaxy clusters / Matteo Cataneo -- Towards testing gravity with cosmic voids / Yan-Chuan Cai -- Astrophysical tests of screened modified gravity / Jeremy Sakstein -- Laboratory constraints / Philippe Brax.
