Journal ArticleDOI
Dynamics of dark energy
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In this article, the authors review the observational evidence for the current accelerated expansion of the universe and present a number of dark energy models in addition to the conventional cosmological constant, paying particular attention to scalar field models such as quintessence, K-essence and tachyon.Abstract:
We review in detail a number of approaches that have been adopted to try and explain the remarkable observation of our accelerating universe. In particular we discuss the arguments for and recent progress made towards understanding the nature of dark energy. We review the observational evidence for the current accelerated expansion of the universe and present a number of dark energy models in addition to the conventional cosmological constant, paying particular attention to scalar field models such as quintessence, K-essence, tachyon, phantom and dilatonic models. The importance of cosmological scaling solutions is emphasized when studying the dynamical system of scalar fields including coupled dark energy. We study the evolution of cosmological perturbations allowing us to confront them with the observation of the Cosmic Microwave Background and Large Scale Structure and demonstrate how it is possible in principle to reconstruct the equation of state of dark energy by also using Supernovae Ia observational data. We also discuss in detail the nature of tracking solutions in cosmology, particle physics and braneworld models of dark energy, the nature of possible future singularities, the effect of higher order curvature terms to avoid a Big Rip singularity, and approaches to modifying gravity which leads to a late-time accelerated expansion without recourse to a new form of dark energy.read more
Citations
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Journal ArticleDOI
Dust of Dark Energy
TL;DR: In this paper, a new class of field theories where energy always flows along timelike geodesics, mimicking in that respect dust, yet which possess non-zero pressure is introduced.
Journal ArticleDOI
Nonminimal curvature-matter coupled wormholes with matter satisfying the null energy condition
TL;DR: In this paper, the exact solutions of wormhole geometries supported by a non-minimal curvature-matter coupling were found, where the nonminimal coupling minimizes the violation of the null energy condition of normal matter at the throat.
Journal ArticleDOI
Cosmological constant from the ghost: A toy model
TL;DR: In this paper, the 2D Schwinger model on a 2-torus and in curved 2D space is analyzed and the departure from Minkowski flatness is found to scale as 1/L, where L is the linear size of the torus.
Journal ArticleDOI
Constraints on scalar-tensor models of dark energy from observational and local gravity tests
Abstract: We construct a family of viable scalar-tensor models of dark energy (DE) which possess a phase of late-time acceleration preceded by a standard matter era, while at the same time satisfying the local gravity constraints (LGC). The coupling $Q$ between the scalar field and the nonrelativistic matter in the Einstein frame is assumed to be constant in our scenario, which is a generalization of $f(R)$ gravity theories corresponding to the coupling $Q=\ensuremath{-}1/\sqrt{6}$. We find that these models can be made compatible with local gravity constraints even when $|Q|$ is of the order of unity through a chameleon mechanism, if the scalar-field potential is chosen to have a sufficiently large mass in the high-curvature regions. We show that these models generally lead to the divergence of the equation of state of DE, which occurs at smaller redshifts as the deviation from the $\ensuremath{\Lambda}\mathrm{CDM}$ model becomes more significant. We also study the evolution of matter density perturbations and employ them to place bounds on the coupling $|Q|$ as well as model parameters of the field potential from observations of the matter power spectrum and the cosmic microwave background (CMB) anisotropies. We find that, as long as $|Q|$ is smaller than the order of unity, there exist allowed parameter regions that are consistent with both observational and local gravity constraints.
Journal ArticleDOI
H i intensity mapping: a single dish approach
Richard A. Battye,Ian Browne,Clive Dickinson,G. Heron,Bruno Maffei,Alkistis Pourtsidou,Alkistis Pourtsidou +6 more
TL;DR: In this paper, the authors proposed a single-dish H I detector for low and high redshift observations with a fixed sensitivity, and showed that at low redshift (z? 0.3), a resolution of?40 arcmin and a survey of?5000 deg 2 is close to optimal.
References
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Journal ArticleDOI
A new look at the statistical model identification
TL;DR: In this article, a new estimate minimum information theoretical criterion estimate (MAICE) is introduced for the purpose of statistical identification, which is free from the ambiguities inherent in the application of conventional hypothesis testing procedure.
Journal ArticleDOI
Estimating the Dimension of a Model
TL;DR: In this paper, the problem of selecting one of a number of models of different dimensions is treated by finding its Bayes solution, and evaluating the leading terms of its asymptotic expansion.
Estimating the dimension of a model
TL;DR: In this paper, the problem of selecting one of a number of models of different dimensions is treated by finding its Bayes solution, and evaluating the leading terms of its asymptotic expansion.
Journal ArticleDOI
Measurements of Omega and Lambda from 42 High-Redshift Supernovae
Saul Perlmutter,Saul Perlmutter,Greg Aldering,Gerson Goldhaber,Gerson Goldhaber,R. A. Knop,Peter Nugent,P. G. Castro,P. G. Castro,Susana E. Deustua,Sebastien Fabbro,Sebastien Fabbro,A. Goobar,A. Goobar,Donald E. Groom,I. M. Hook,I. M. Hook,A. G. Kim,A. G. Kim,A. G. Kim,M. Y. Kim,Julia C. Lee,Julia C. Lee,Nelson J. Nunes,Nelson J. Nunes,Reynald Pain,Reynald Pain,C. R. Pennypacker,C. R. Pennypacker,Robert Quimby,Christopher Lidman,Richard S. Ellis,Mike Irwin,Richard G. McMahon,Pilar Ruiz-Lapuente,Nicholas A. Walton,Bradley E. Schaefer,B. J. Boyle,Alexei V. Filippenko,Thomas Matheson,A. S. Fruchter,Nino Panagia,Nino Panagia,Heidi Jo Newberg,Warrick J. Couch +44 more
TL;DR: In this paper, the mass density, Omega_M, and cosmological-constant energy density of the universe were measured using the analysis of 42 Type Ia supernovae discovered by the Supernova Cosmology project.
Journal ArticleDOI
Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant
Adam G. Riess,Alexei V. Filippenko,Peter Challis,Alejandro Clocchiatti,Alan H. Diercks,Peter M. Garnavich,R. L. Gilliland,Craig J. Hogan,Saurabh Jha,Robert P. Kirshner,Bruno Leibundgut,Mark M. Phillips,David J Reiss,Brian P. Schmidt,R. A. Schommer,R. Chris Smith,R. Chris Smith,Jason Spyromilio,Christopher W. Stubbs,Nicholas B. Suntzeff,John L. Tonry +20 more
TL;DR: In this article, the authors used spectral and photometric observations of 10 Type Ia supernovae (SNe Ia) in the redshift range 0.16 " z " 0.62.
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