Energy Definition and Dark Energy: A Thermodynamic Analysis

Moradpour, H.; Graça, J. P. Morais; Lobo, Iarley P.; Salako, Ines G.

doi:10.1155/2018/7124730

Cited by 6 publications

(3 citation statements)

References 58 publications

(183 reference statements)

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“…( 5) in order to introduce the generalized energy-momentum tensor Θ µν = T µν − (κ ′ λ ′ )/(4κ ′ λ ′ − 1)T g µν which finally leads to the GR counterpart form of the Rastall field equations, given as G µν = κ ′ Θ µν . In this manner, although the obtained field equations are similar to those of GR, their solutions for T µν differ in general from those of GR [66,69], a result confirmed by various observational data, see e.g., [45,54,69] and references therein).…”

Section: Rastall Theory and A Model For Varying Gsupporting

confidence: 74%

“…In GRT, cosmological scenarios [43,59,62,63] imply the power of non-minimal coupling in i) providing both singular and non-singular universes, ii) describing the particle production process, iii) avoiding the coincidence problem, and iv) playing the role of dark energy (unlike the original Rastall theory [43,64]). In this regard, thermodynamically it has also been shown that the confusion in defining energy and some of its outcomes which may lead to the OCL generalization (or equivalently, the breakdown of OCL) could make the cosmos dark [65,66].…”

Section: Introductionmentioning

confidence: 99%

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Non-minimal coupling inspires the Dirac cosmological model

Moradpour,

Shabani,

Ziaie

et al. 2021

Preprint

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In the framework of the generalized Rastall theory (GRT), we study the ability of a non-minimal coupling between geometry and matter fields in order to provide a setting which allows for a variable G during the cosmic evolution. In this regard, the compatibility of this theory with Dirac hypothesis on the variations of G is investigated, and additionally, the possibility of obtaining the current accelerated universe is also addressed. In summary, our study indicates that, in GRT, having in hand the G profile, one may find the corresponding non-minimal coupling between the energy source and geometry and vise versa, in a compatible way with the current accelerated universe.

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Section: Rastall Theory and A Model For Varying Gsupporting

confidence: 74%

Section: Introductionmentioning

confidence: 99%

Non-minimal coupling inspires the Dirac cosmological model

Moradpour,

Shabani,

Ziaie

et al. 2021

Preprint

View full text Add to dashboard Cite

show abstract

“…A simple generalization for the energy that overcomes some of the thermodynamics inconsistencies is the Komar energy, which is given by U K = (ρ + 3 p)V , see for instance the Refs. [65,66], where some cosmological features of this energy are explored in detail. Note that when the Komar energy is considered we are taking into account the effects of the cosmological fluid pressure, therefore we have a more realistic description of the cosmic evolution.…”

Section: Generalized Form Of the Energymentioning

confidence: 99%

Non-zero torsion and late cosmology

2020

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In this work, we study some thermodynamical aspects associated with torsion in a flat FLRW spacetime cosmic evolution. By implementing two Ansatze for the torsion term, we find that the model admits a phantom regime or a quintessence behavior. This scheme differs from the CDM model at the thermodynamical level. The resulting cosmic expansion is not adiabatic, the fulfillment of the second law of thermodynamics requires a positive torsion term, and the temperature of the cosmic fluid is always positive. The entropy of the torsion phantom scenario is negative, but introducing chemical potential solves this issue. For a Dirac-Milne type Universe, the torsion leads to a growing behavior for the temperature of the fluid but has no incidence on the rate of expansion.

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Modeling holographic dark energy with particle and future horizons

Cruz

Lepe

2020

Nuclear Physics B

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In this work we explore some properties and their implications at thermodynamics level of the particle and future horizons when are considered as candidates to model the dark energy within a holographic context for a flat Friedmann-Lemaitre-Robertson-Walker universe. Under these considerations we can find that the model admits a genuine big rip singularity when the dark energy density is sketched by the future horizon, in consequence the resulting parameter state can cross to the phantom regime. For the particle horizon case the cosmological fluid can emulate ordinary matter. Additionally, the coincidence parameter has a decreasing behavior for the future horizon. On the other hand, from the interacting scheme for cosmological fluids we obtain that in the dark energy -dark matter interaction, the dark energy fluid will have negative entropy production, therefore the second law of thermodynamics can not be guaranteed in this sector. PACS numbers: 95.36.+x, 95.35.+d,

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Energy Definition and Dark Energy: A Thermodynamic Analysis

Cited by 6 publications

References 58 publications

Non-minimal coupling inspires the Dirac cosmological model

Non-minimal coupling inspires the Dirac cosmological model

Non-zero torsion and late cosmology

Modeling holographic dark energy with particle and future horizons

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