Dark Energy

Li, Miao; Li, Xiao Dong; Wang, Shuang; Wang, Yi

doi:10.1088/0253-6102/56/3/24

Cited by 770 publications

(576 citation statements)

References 1,089 publications

(1,137 reference statements)

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“…Nevertheless, these dynamical dark energy models offer the simplest extension of ΛCDM and have been extensively studied (see for example ), and often go under the name quintessence. For reviews and further references, see [85][86][87][88][89][90][91][92].…”

Section: Dynamical Dark Energymentioning

confidence: 99%

Beyond the cosmological standard model

et al. 2015

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After a decade and a half of research motivated by the accelerating universe, theory and experiment have a reached a certain level of maturity. The development of theoretical models beyond Λ or smooth dark energy, often called modified gravity, has led to broader insights into a path forward, and a host of observational and experimental tests have been developed. In this review we present the current state of the field and describe a framework for anticipating developments in the next decade. We identify the guiding principles for rigorous and consistent modifications of the standard model, and discuss the prospects for empirical tests.We begin by reviewing recent attempts to consistently modify Einstein gravity in the infrared, focusing on the notion that additional degrees of freedom introduced by the modification must "screen" themselves from local tests of gravity. We categorize screening mechanisms into three broad classes: mechanisms which become active in regions of high Newtonian potential, those in which first derivatives of the field become important, and those for which second derivatives of the field are important. Examples of the first class, such as f (R) gravity, employ the familiar chameleon or symmetron mechanisms, whereas examples of the last class are galileon and massive gravity theories, employing the Vainshtein mechanism. In each case, we describe the theories as effective theories and discuss prospects for completion in a more fundamental theory. We describe experimental tests of each class of theories, summarizing laboratory and solar system tests and describing in some detail astrophysical and cosmological tests. Finally, we discuss prospects for future tests which will be sensitive to different signatures of new physics in the gravitational sector.The review is structured so that those parts that are more relevant to theorists vs. observers/experimentalists are clearly indicated, in the hope that this will serve as a useful reference for both audiences, as well as helping those interested in bridging the gap between them.

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Section: Dynamical Dark Energymentioning

confidence: 99%

Beyond the cosmological standard model

et al. 2015

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“…On the other hand, in recent years, a wealth of dynamical DE models with a time-varying EoS has been proposed (Copeland et al 2006;Li et al 2011;Bamba et al 2012). Observationally, the latest astronomical data from SNe Ia, CMB and BAO experiments show that dynamical DE models with time-varying EoS parameter are mildly favored (Zhao et al 2012;Alam et al 2004;Gong 2005;Gong & Zhang 2005;Huterer & Cooray 2005;Wang & Tegmark 2005).…”

Section: Introductionmentioning

confidence: 99%

Evolution of spherical overdensities in holographic dark energy models

Naderi¹,

Malekjani²,

Pace³

2015

Monthly Notices of the Royal Astronomical Society

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In this work we investigate the spherical collapse model in flat FRW dark energy universes. We consider the Holographic Dark Energy (HDE) model as a dynamical dark energy scenario with a slowly time-varying equation-of-state (EoS) parameter w de in order to evaluate the effects of the dark energy component on structure formation in the universe. We first calculate the evolution of density perturbations in the linear regime for both phantom and quintessence behavior of the HDE model and compare the results with standard Einstein-de Sitter (EdS) and ΛCDM models. We then calculate the evolution of two characterizing parameters in the spherical collapse model, i.e., the linear density threshold δ c and the virial overdensity parameter ∆ vir . We show that in HDE cosmologies the growth factor g(a) and the linear overdensity parameter δ c fall behind the values for a ΛCDM universe while the virial overdensity ∆ vir is larger in HDE models than in the ΛCDM model. We also show that the ratio between the radius of the spherical perturbations at the virialization and turn-around time is smaller in HDE cosmologies than that predicted in a ΛCDM universe. Hence the growth of structures starts earlier in HDE models than in ΛCDM cosmologies and more concentrated objects can form in this case. It has been shown that the non-vanishing surface pressure leads to smaller virial radius and larger virial overdensity ∆ vir . We compare the predicted number of halos in HDE cosmologies and find out that in general this value is smaller than for ΛCDM models at higher redshifts and we compare different mass function prescriptions. Finally, we compare the results of the HDE models with observations.

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“…V, highlighting the testable prediction of a zero tensor-to-scalar ratio in the primordial power spectra. Reviews can be found in [30][31][32] for dark energy and [33][34][35][36][37] for inflation.…”

Section: Introductionmentioning

confidence: 99%

Dark energy and inflation with a volume normalized action

Gabadadze

2018

Phys. Rev. D

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In the theories described by a volume normalized action functional, an arbitrary cosmological constant is eliminated from the physical picture of our Universe, and dynamical alternatives must be responsible for today's accelerated expansion as well as the conjectured early-time inflation in the Universe. A few wellknown such scenarios realized by a single homogeneous scalar field are examined in this new context, and their diverse fates are elucidated. Typical inflationary models are not affected at the level of the background evolution, and also give rise to the scalar perturbations equivalent to those obtained in the standard general relativity; however, the primordial quantum tensor fluctuations are absent in the new framework, irrespective of the inflationary model. As a consequence, our proposal would be ruled out should the primordial tensor modes, or their indirect consequences, be observed experimentally.

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Dark Energy

Abstract: We review the problem of dark energy, including a survey of theoretical models and some aspects of numerical studies.

Cited by 770 publications

References 1,089 publications

Beyond the cosmological standard model

Beyond the cosmological standard model

Evolution of spherical overdensities in holographic dark energy models

Dark energy and inflation with a volume normalized action

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