Observational constraints and stability in viscous   gravity

Rezaei, T. Mirzaei; Amani, Alireza; Yusofi, E.; Rouhani, S.; Ramzanpour, M. A.

doi:10.1139/cjp-2020-0174

Cited by 10 publications

(4 citation statements)

References 81 publications

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“…( 14) can be regarded as a "good vielbein". Similarly, in the FRW cosmological models the f (T, T ) gravitational dynamics preserves the form of the usual Friedmann equations (two equations) [48,49,57,62].…”

Section: Brane In F (T T ) Gravitymentioning

confidence: 94%

First-order formalism for thick branes in $f(T,\mathcal{T})$ gravity

Moreira,

Lima,

Silva

et al. 2021

Preprint

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In this paper we study the thick brane scenario constructed in the recently proposed f (T, T ) theories of gravity, where T is called the torsion scalar and T is the trace of the energy-momentum tensor. We use the first-order formalism to find analytical solutions for models that include a scalar field as a source. In particular, we describe two interesting case in which in the first we obtain a double-kink solution, which generates a splitting in the brane. In the second case, proper management of a kink solution obtained generates a splitting in the brane intensified by the torsion parameter, evinced by the energy density components satisfying the weak and strong energy conditions. In addition, we investigate the behavior of the gravitational perturbations in this scenario.The parameters that control the torsion and the trace of the energy-momentum tensor tend to shift the massive modes to the core of the brane, keeping a gapless non-localizable and stable tower of massive modes and producing more localized massless modes.

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Section: Brane In F (T T ) Gravitymentioning

confidence: 94%

First-order formalism for thick branes in $f(T,\mathcal{T})$ gravity

Moreira,

Lima,

Silva

et al. 2021

Preprint

View full text Add to dashboard Cite

show abstract

Section: Brane In F (T T ) Gravitymentioning

confidence: 94%

“…This new modified gravity model has gained a lot of attention recently due significant results obtained in cosmological perturbations and thermodynamics [48][49][50][51][52][53][54][55][56]. Also, interesting astrophysical applications [57][58][59][60], new developments in dark energy [61,62], and in a viable alternative to black hole (called Gravstar) [63], were obtained through ideas of f (T, T ) gravity.…”

Section: Introductionmentioning

confidence: 99%

First-order formalism for thick branes in $$f(T,{\mathscr {T}})$$ gravity

et al. 2021

View full text Add to dashboard Cite

In this paper we study the thick brane scenario constructed in the recently proposed $$f(T,{\mathscr {T}})$$ f ( T , T ) theories of gravity, where T is called the torsion scalar and $${\mathscr {T}}$$ T is the trace of the energy–momentum tensor. We use the first-order formalism to find analytical solutions for models that include a scalar field as a source. In particular, we describe two interesting case in which in the first we obtain a double-kink solution, which generates a splitting in the brane. In the second case, proper management of a kink solution obtained generates a splitting in the brane intensified by the torsion parameter, evinced by the energy density components satisfying the weak and strong energy conditions. In addition, we investigate the behavior of the gravitational perturbations in this scenario. The parameters that control the torsion and the trace of the energy–momentum tensor tend to shift the massive modes to the core of the brane, keeping a gapless non-localizable and stable tower of massive modes and producing more localized massless modes.

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“…For that the universe is considered more realistic, we take the bulk viscosity fluid instead of the perfect fluid. In this case, the bulk viscosity creates internal friction that converts the kinetic energy of the particles into heat [99][100][101][102]. This in turn can be an appropriate idea to describe the accelerated universe in late time.…”

Section: Introductionmentioning

confidence: 99%

Extended Bose-Einstein condensate dark matter in viscous Gauss-Bonnet gravity

Mahichi,

Amani,

Ramzanpour

2021

Preprint

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In this paper, we study the F (R, G) gravity model with an interacting model by flat-FRW metric in a viscous fluid. We consider that the universe dominates with components of dark matter and dark energy. This means that the dark matter component derives from Extended Bose-Einstein Condensate (EBEC) and the components of dark energy arise from the F (R, G) gravity. After obtaining the Einstein equation, the energy density and the pressure of dark energy are written in terms of the geometries of the curvature and the Gauss-Bonnet terms, and components of dark matter and viscous fluid. Also, the corresponding continuity equations are written with the presence of interaction terms. In what follows, we employ the EBEC regime instead of the normal dark matter by the dark matter Equation of State (EoS) as p dm = αρ dm + βρ 2 dm , which arises from the gravitational form. The EoS can be expressed from the perspective of the virial expansion, in which the first and second terms represent normal dark matter and quantum ground state. Next, the corresponding Friedmann equations reconstruct in terms of the redshift parameter, then by using the scenario of the power-law cosmology for the scale factor, we fit the present model with the Hubble amounts of 51 supernova data by the likelihood analysis. In that case, we acquire the cosmological parameters of dark energy in terms of the redshift parameter, and by plotting these graphs, we see that the universe is currently undergoing an accelerated expansion phase.Finally, we investigate the stability of the present model with the sound speed parameter.

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Observational constraints and stability in viscous gravity

Cited by 10 publications

References 81 publications

First-order formalism for thick branes in $f(T,\mathcal{T})$ gravity

First-order formalism for thick branes in $f(T,\mathcal{T})$ gravity

First-order formalism for thick branes in $$f(T,{\mathscr {T}})$$ gravity

Extended Bose-Einstein condensate dark matter in viscous Gauss-Bonnet gravity

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