Unified dark fluid in Brans–Dicke theory

Tripathy, S. K.; Behera, Dipanjali; Mishra, B.

doi:10.1140/epjc/s10052-015-3371-3

Cited by 48 publications

(25 citation statements)

References 113 publications

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“…Hence LRSBI models can not provide accelerating models without the contributions coming from magnetic field, scalar field or cosmic string. However, in presence of cosmic strings, magnetic field or scalar fields the situation gets modified and accelerating models are achieved [33,60]. In the present work, we are interested in the late time cosmic dynamics with preconceived idea of accelerated expansion and therefore, we will force this functional to be non zero.…”

Section: Basic Formalismmentioning

confidence: 99%

“…Basing upon the requirements, the parametrized forms are tuned to get viable models describing dark energy. In recent times, there have also been a growing interest in a unified dark fluid where the contributions coming from both the dark energy and dark matter part are handled through a unified dark equation of state which may be linear or non linear in energy density [29][30][31][32][33]. The single unified dark adiabatic cosmic fluid is able to explain most of the recent observational data.…”

Section: Introductionmentioning

confidence: 99%

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Anisotropic dark energy model with a hybrid scale factor

Mishra

Tripathy

2015

Mod. Phys. Lett. A

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Anisotropic dark energy model with dynamic pressure anisotropies along different spatial directions is constructed at the backdrop of a spatially homogeneous diagonal Bianchi type V (BV ) space-time in the framework of General Relativity. A time varying deceleration parameter generating a hybrid scale factor is considered to simulate a cosmic transition from early deceleration to late time acceleration. We found that the pressure anisotropies along the y− and z− axes evolve dynamically and continue along with the cosmic expansion without being subsided even at late times. The anisotropic pressure along the x−axis becomes equal to the mean fluid pressure. At a late phase of cosmic evolution, the model enters into a phantom region. From a statefinder diagnosis, it is found that the model overlaps with ΛCDM at late phase of cosmic time.

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Section: Basic Formalismmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Anisotropic dark energy model with a hybrid scale factor

Mishra

Tripathy

2015

Mod. Phys. Lett. A

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“…First, it should be stressed that recently in [26], the f (R, T ) theories have been interpreted as a generalization of the Brans-Dicke model [52][53][54][55][56]. As argued by the authors in [26], the extra terms in the f (R, T ) FEs may play the role of additional terms of effective gravitational and cosmological "constants" G eff and eff .…”

Section: Another Further Work May Rise From An Alternative Form For Fmentioning

confidence: 99%

A complete cosmological scenario from $$f(R,T^{\phi })$$ f ( R , T ϕ )

Moraes¹,

Santos²

2016

Eur. Phys. J. C

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Recent elaborated by Harko et al., the f (R, T ) theories of gravity allow one to contemplate an optimistic alternative to dark energy, for which R and T stand for the Ricci scalar and the trace of the energy-momentum tensor, respectively. Although the literature has shown that the T dependence on the gravitational part of the action -which is due to the consideration of quantum effects -may induce some novel features in the scope of late-time cosmological dynamics, in the radiation-dominated universe, when T = 0, no contributions seem to arise from such theories. Apparently, f (R, T ) contributions to a radiation-dominated universe may arise only from the f (R, T φ ) approach, which is nothing but the f (R, T ) gravity in the case of a selfinteracting scalar field whose trace of the energy-momentum tensor is T φ . We intend, in this article, to show how f (R, T φ ) theories of gravity can contribute to the study of the primordial stages of the universe. Our results predict a graceful exit from an inflationary stage to a radiation-dominated era. They also predict a late-time cosmic acceleration after a matter-dominated phase, enabling the f (R, T φ ) theories to describe, in a self-consistent way, all the different stages of the dynamics of the universe.

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“…For observational and theoretical motivations, several extended versions of the BD theory have been developed, such as adding a potential term to the original BD theory [35], assuming the coupling constant ω to be variable with respect to time [36,37], generalizing φ to be a function f (φ) in the coupling term φR [38,39], choosing a higher-dimension geometry in the BD theory [40], etc. The applications of these extended BD theories have been investigated widely, such as at the aspects of cosmology [41][42][43], weak-field approximation [44], observational constraints [45,46], and so on [47][48][49].…”

Section: Introductionmentioning

confidence: 99%

Linearized physics and gravitational-waves polarizations in the Palatini formalism of GBD theory

Guo

et al. 2020

Physics Letters B

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A generalized Brans-Dicke (GBD) theory in the framework of Palatini formalism are proposed in this paper. We derive the field equations by using the variational approach and obtain the linearized equations by using the weak-field approximation method. We show various properties of the geometrical scalar field in the Palatini-formalism of GBD theory: it is massless and sourcefree, which are different from the results given in the metric-formalism of GBD theory. Also, we investigate the polarization modes of gravitational waves (GWs) by using the the geodesic deviation method and the Newman-Penrose method in the Palatini-GBD theory. It is observed that there are three polarizations modes and four oscillation in the Palatini-GBD theory. Concretely, they are the two transverse tensor (+) and (×) standard polarization modes, and one breathing mode (with two oscillation). The results of GWs polarization in the Palatini-GBD theory are different from that in the metric-GBD theory, where there are four polarizations modes: the two standard tensorial modes (+ and ×), a scalar breathing mode, and a massive scalar mode that is a mix of the longitudinal and the breathing polarization. Comparing with the Palatini-f (R) theory and the General Relativity, we can see that the extra breathing mode of GWs polarization can be found in the Palatini-GBD theory. At last, the expression of the parameterized post Newton (PPN) parameter is derived, which could pass through the experimental test.

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Unified dark fluid in Brans–Dicke theory

Cited by 48 publications

References 113 publications

Anisotropic dark energy model with a hybrid scale factor

Anisotropic dark energy model with a hybrid scale factor

A complete cosmological scenario from $$f(R,T^{\phi })$$ f ( R , T ϕ )

Linearized physics and gravitational-waves polarizations in the Palatini formalism of GBD theory

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