Accelerated expansion of the Universe in a higher dimensional modified gravity with Euler-Poincaré terms

Akarsu, Özgür; Dereli, Tekin; Oflaz, Neslihan

doi:10.1088/0264-9381/32/21/215009

Cited by 5 publications

(7 citation statements)

References 56 publications

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“…27,28 While GR can explain it through the cosmological constant, which suffers from a serious fine-tuning problem, 29,30 alternative gravity can well address this particular issue. [31][32][33] Also, a phantom fluid, that is, a fluid with equation of state (EoS) parameter ω < −1, permeating the universe could well fit the observations indicating the cosmic acceleration. [34][35][36] From some particular well addressed cases for the WHs redshift and shape functions, in this article we will obtain the material content solutions for WHs.…”

Section: Introductionmentioning

confidence: 80%

Phantom fluid supporting traversable wormholes in alternative gravity with extra material terms

Sahoo

Moraes

Ribeiro

2018

Int. J. Mod. Phys. D

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Wormholes are tunnels connecting different regions in space-time. They were obtained originally as a solution for Einstein's General Relativity theory and according to this theory they need to be filled by an exotic kind of anisotropic matter. In the present sense, by "exotic matter" we mean matter that does not satisfy the energy conditions. In this article we propose the modelling of wormholes within an alternative gravity theory that proposes an extra material (rather than geometrical) term in its gravitational action. Our solutions are obtained from well-known particular cases of the wormhole metric potentials, named redshift and shape functions, and yield the wormholes to be filled by a phantom fluid, that is, a fluid with equation of state parameter ω < −1. In possession of the solutions for the wormhole material content, we also apply the energy conditions to them. The features of those are carefully discussed.

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Section: Introductionmentioning

confidence: 80%

Phantom fluid supporting traversable wormholes in alternative gravity with extra material terms

Sahoo

Moraes

Ribeiro

2018

Int. J. Mod. Phys. D

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“…In this work, we are interested in the higher-dimensional cosmologies that yield constant higher-dimensional volume, and accordingly we proceed with the following ansatz, as done in Refs. [25,27,30];…”

Section: The Modelmentioning

confidence: 99%

“…There is an interesting class in which the external and internal dimensions are dynamical but the total volume of the higher-dimensional space remains constant [6,7,17,18,24,27,30]. In particular, Dereli and Tucker [7], inspired by the inflationary model introduced by Guth [39], constructed a higher-dimensional general relativistic cosmological model assuming both external and internal spaces are flat, homogeneous and isotropic, but while the external space expands exponentially and the internal space contracts exponentially.…”

Section: Introductionmentioning

confidence: 99%

“…In Ref. [30], Akarsu, Dereli, and Oflaz consider a higher-dimensional modified gravity theory with an action that includes dimensionally continued Euler-Poincaré forms up to second order (known also as Gauss-Bonnet term) [44], which live in the presence of extra dimensions, assuming a matter field that yields different dynamical pressures in the external and internal spaces. It is shown that the second order Euler-Poincaré term in the constructions of higher-dimensional steady state cosmologies could be crucial in finding effectively (1 + 3)-dimensional universe models resembling the standard ΛCDM model.…”

Section: Introductionmentioning

confidence: 99%

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ACDM cosmology with a quiescent anisotropy in a higher dimensional steady state universe

Akarsu

Dereli

Katırcı

2022

J. Phys.: Conf. Ser.

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In this work, which follows a series of studies on the higher-dimensional steady state universe idea and prepared for Professor Tekin Dereli’s Festschrift, we show the infuence of the dynamical internal (unobservable) space on the evolution of the possible anisotropy of the external (observable) space. We obtain mathematically exactly the same Friedmann equation of the standard ΛCDM model for the external space, but with some remarkable physical diferences. In particular, the higher-dimensional negative cosmological constant plays the role of the four-dimensional positive cosmological constant and the expansion anisotropy, viz., the shear scalar, of the external space mimics a negative cosmological constant; it would mimic a stif fuid when allowed on top of the standard ΛCDM model. This latter feature gives us the opportunity to manipulate the CMB quadrupole temperature fuctuation, suggesting a possible answer to the fact that its observed value is lower than that predicted by the standard ΛCDM model.

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“…Different aspects of the accelerated expansion of the Universe have been investigated [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. The influence of inhomogeneities on the global expansion factor by averaging the Friedmann equation has been calculated [5].…”

Section: Introductionmentioning

confidence: 99%

Accelerated expansion of the Universe in the presence of dark matter pressure

Rezaei

2020

Can. J. Phys.

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Expansion dynamics of the Universe is one of the important subjects in modern cosmology. The dark energy equation of state determines this dynamics so that the Universe is in an accelerating phase. However, the dark matter can also affect the accelerated expansion of the Universe through its equation of state. In the present work, we explore the expansion dynamics of the Universe in the presence of dark matter pressure. In this regard, applying the dark matter equation of state from the observational data related to the rotational curves of galaxies, we calculate the evolution of dark matter density. Moreover, the Hubble parameter, history of scale factor, luminosity distance, and deceleration parameter are studied while the dark matter pressure is taken into account. Our results verify that the dark matter pressure leads to the higher values of the Hubble parameter at each redshift and the expansion of the Universe grows due to the DM

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Accelerated expansion of the Universe in a higher dimensional modified gravity with Euler-Poincaré terms

Cited by 5 publications

References 56 publications

Phantom fluid supporting traversable wormholes in alternative gravity with extra material terms

Phantom fluid supporting traversable wormholes in alternative gravity with extra material terms

ACDM cosmology with a quiescent anisotropy in a higher dimensional steady state universe

Accelerated expansion of the Universe in the presence of dark matter pressure

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