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Cosmology

About: Cosmology is a research topic. Over the lifetime, 18004 publications have been published within this topic receiving 631028 citations. The topic is also known as: physical cosmology & cosmologies.


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Journal ArticleDOI
TL;DR: In this article, the cosmological implications of holographic dark energy density in the Gauss-Bonnet framework were investigated, and it was shown that there is a correspondence between the holographic light energy scenario in flat universe and the phantom dark energy model in the framework of Gauss−Bonnet theory with a potential.

141 citations

Journal ArticleDOI
TL;DR: In this paper, infinite density singularities may be shown to occur in Friedmann-Robertson-Walker universes and orthogonal spatially homogeneous universes, but very different behaviours are possible in tilted homogeneous cosmologies.

141 citations

Book
06 Mar 2008
TL;DR: In this paper, the concept of distance in cosmology was introduced and the first Lap in CMB Anisotropies Improved Fluid Description of Pre-Decoupling Physics Kinetic Hierarchies of Multipole Moments Early Initial Conditions Surfing on the Gauges Interacting Fluids Spectator Fields Appendices: The Concept of Distance in Cosmology Kinetic Description of Hot Plasmas Scalar Modes of the Geometry Metric Fluctuations: Gauge Independent Treatment
Abstract: Why CMB Physics Electromagnetic Emission of the Observable Universe From CMB to the Standard Cosmological Model Problems with the Standard Cosmological Model (SCM) Beyond the SCM Essentials of Inflationary Dynamics Inhomogeneities in FRW Models The First Lap in CMB Anisotropies Improved Fluid Description of Pre-Decoupling Physics Kinetic Hierarchies of Multipole Moments Early Initial Conditions Surfing on the Gauges Interacting Fluids Spectator Fields Appendices: The Concept of Distance in Cosmology Kinetic Description of Hot Plasmas Scalar Modes of the Geometry Metric Fluctuations: Gauge Independent Treatment

141 citations

01 Jan 1981
TL;DR: In this paper, the Compton-getting interpretation of the dipole anisotropy in the microwave background is presented as a diagnostic of the weak asymmetry exhibited by the cosmic X-ray background.
Abstract: As the sky in the microwave band is dominated by a cosmic background, so too is the X-ray sky. In this report, the experimental approach used for measuring the X-ray background is explained and evaluated. The Compton-Getting interpretation of the dipole anisotropy in the microwave background is presented as a diagnostic of the weak asymmetry exhibited by the cosmic X-ray background. Spectral characteristics and spatial fluctuations of this X-ray background are described and then discussed within the context of what is known about individual extragalactic sources. It is concluded that the bulk of the cosmic X-ray background is yet to be understood. The critical apparatus of modern cosmology is reviewed and applied to this problem, providing constraints and indicating possible avenues for achieving a solution. The outlook for obtaining the new data called for is examined in terms of experiments now in preparation.

141 citations

Journal ArticleDOI
TL;DR: In this article, the authors present a detailed analysis of the inflationary dynamics of LQC using analytical and numerical methods, and show that the probability of a sufficiently long slow roll inflation which is compatible with the seven year WMAP data is very close to 1.
Abstract: Inflationary models of the early universe provide a natural mechanism for the formation of large scale structure. This success brings to forefront the question of naturalness: Does a sufficiently long slow roll inflation occur generically or does it require a careful fine tuning of initial parameters? In recent years there has been considerable controversy on this issue (Hollands and Wald in Gen Relativ Gravit, 34:2043, 2002; Kofman et al. in J High Energy Phys 10:057, 2002); (Gibbons and Turok in Phys Rev D 77:063516, 2008). In particular, for a quadratic potential, Kofman et al. (J High Energy Phys 10:057, 2002) have argued that the probability of inflation with at least 65 e-foldings is close to one, while Gibbons and Turok (Phys Rev D 77:063516, 2008) have argued that this probability is suppressed by a factor of ~10−85. We first clarify that such dramatically different predictions can arise because the required measure on the space of solutions is intrinsically ambiguous in general relativity. We then show that this ambiguity can be naturally resolved in loop quantum cosmology (LQC) because the big bang is replaced by a big bounce and the bounce surface can be used to introduce the structure necessary to specify a satisfactory measure. The second goal of the paper is to present a detailed analysis of the inflationary dynamics of LQC using analytical and numerical methods. By combining this information with the measure on the space of solutions, we address a sharper question than those investigated in Kofman et al. (J High Energy Phys 10:057, 2002), Gibbons and Turok (Phys Rev D 77:063516, 2008), Ashtekar and Sloan (Phys Lett B 694:108, 2010): What is the probability of a sufficiently long slow roll inflation which is compatible with the seven year WMAP data? We show that the probability is very close to 1. The material is so organized that cosmologists who may be more interested in the inflationary dynamics in LQC than in the subtleties associated with measures can skip that material without loss of continuity.

140 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20241
2023768
20221,518
2021737
2020784
2019782