Cosmological Chaplygin gas as modified gravity

Elmardi, Maye; Abebe, Amare

doi:10.1088/1742-6596/905/1/012015

Cited by 7 publications

(9 citation statements)

References 35 publications

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“…, (17) where K = C3 A , and C 3 is a constant of integration. Therefore, we now have an equation for the energy density in terms of the scale factor.…”

Section: B the Deceleration Parameter In Mcg Cosmologymentioning

confidence: 99%

Confronting the Chaplygin gas with data: background and perturbed cosmic dynamics

Hough¹,

Sahlu²,

Sami³

et al. 2021

Preprint

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In this paper, we undertake a unified study of background dynamics and cosmological perturbations in the presence of the Chaplygin gas. This is done by first constraining the background cosmological parameters of different Chaplygin gas models with SNIa data, and then feeding these observationally constrained parameters in the analysis of cosmological perturbations. Based on the statistical criteria we followed, none of the models has a substantial observational support but we show that the so-called 'original' and 'generalized' Chaplygin gas models have some observational support and less observational support, respectively, whereas the 'modified' and 'modified generalized' Chaplygin gas models miss out on the less observational support category but cannot be ruled out. The so-called 'generalized cosmic Chaplygin gas' model, on the other hand, falls under the no observational support category of the statistical criterion and can be ruled out. We follow the 1 + 3 covariant formalism of perturbation theory and derive the evolution equations of the fluctuations in the matter density contrast of the matter-Chaplygin gas system for the models with some or less statistical support. The solutions to these coupled systems of equations are then computed in both short-wavelength and long-wavelength modes.

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“…, (17) where K = C3 A , and C 3 is a constant of integration. Therefore, we now have an equation for the energy density in terms of the scale factor.…”

Section: B the Deceleration Parameter In Mcg Cosmologymentioning

confidence: 99%

Confronting the Chaplygin gas with data: background and perturbed cosmic dynamics

Hough¹,

Sahlu²,

Sami³

et al. 2021

Preprint

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“…It is important to clarify the specific role of each three of them on driving the evolution of the Universe. For example, the effects of a Chaplygin gas can be accounted for also by an appropriate f (R) theory [70], or the effects of dark matter can be mimicked by a non-local gravitational theory [71]. These claims triggered a line of research trying to break the possible degeneracy between physically and conceptually different frameworks [72][73][74].…”

Section: Discussionmentioning

confidence: 99%

Phase space analysis and singularity classification for linearly interacting dark energy models

2020

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In this paper, applying the Hartman-Grobman theorem we carry out a qualitative late-time analysis of some unified dark energy-matter Friedmann cosmological models, where the two interact through linear energy exchanges, and the dark energy fluid obeys to the dynamical equation of state of Redlich-Kwong, Modified Berthelot, and Dieterici respectively. The identification of appropriate late-time attractors allows to restrict the range of validity of the free parameters of the models under investigation. We show that the strength of deviation from an ideal fluid for the dark energy does not influence the stability of the late-time attractors, as well as the values of all the cosmological parameters at equilibrium, but for the Hubble function (which represents the age of the universe). Our analysis also shows that a singularity in the effective equation of state parameter for the dark energy fluid is not possible within this class of models.

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“…(23) and (24) respectively, while other f (T ) gravity models such as f 3 (T ) and f 4 (T ) in Eqs. (29) and (30) go to zero. By substituting Eqs.…”

Section: Radiation-torsion Systemmentioning

confidence: 99%

“…A cosmological fluid of particular interest in recent years is the so-called CG. It is a fluid model proposed as a candidate for a unified description of dark matter and dark energy [4,29,34], and its cosmological scenarios are widely presented in the literature. In this work, we consider the torsion fluid as an exotic fluid with equations of state similar to the ones for three variants of the CG model and we reconstruct f (T ) gravity toy models corresponding to the original, generalized and modified generalized models.…”

Section: The Chaplygin Gas As a Model Of Modified Teleparallel Gravit...mentioning

confidence: 99%

“…The Chaplygin gas (CG), first introduced by Chaplygin [22], had a non-cosmological origin but has recently gained new attention in cosmology due to its negative pressure. Together with a Friedman-Lemaître-Robertson-Walker (FLRW) background in the GR framework, this model can explain the cosmic expansion history for a Universe filled with an exotic background fluid [23][24][25][26][27][28][29], but has recently been studied in the context of modified gravity theories as well [27,28,30]. Although the model mimics earlyand late-time cosmic evolution scenarios in the asymptotic limits, certain technical issues remain unresolved for it to be the final candidate for a dark fluid, such as the issues of large-scale structure formation and the violation of causality due to a negative speed of sound associated with the fluid.…”

Section: Introductionmentioning

confidence: 99%

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The Chaplygin gas as a model for modified teleparallel gravity?

et al. 2019

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This paper explores the possibility of treating the exotic Chaplygin-gas (CG) fluid model as some manifestation of an f (T ) gravitation. To this end, we use the different cosmological CG equations of state, compare them with the equation of state for the modified teleparallel gravity and reconstruct the corresponding Lagrangian densities. We then explicitly derive the equation of state parameter of the torsion fluid w T and study its evolution for vacuum-torsion, radiation-torsion, dust-torsion, stiff fluidtorsion and radiation-dust-torsion multi-fluid systems. The obtained Lagrangians have, in general, matter dependence due to the matter-torsion coupling appearing in the energy density and pressure terms of the modified teleparallel gravity theory. For the simplest CG models, however, it is possibly to reconstruct f (T ) Lagrangians that depend explicitly on the torsion scalar T only. The preliminary results show that, in addition to providing Chaplygin-gas-like solutions to the modified teleparallel gravitation, which naturally behave like dark matter and dark energy at early and late times respectively, the technique can be used to overcome some of the challenges attributed to the CG cosmological alternative. 749

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Cosmological Chaplygin gas as modified gravity

Cited by 7 publications

References 35 publications

Confronting the Chaplygin gas with data: background and perturbed cosmic dynamics

Confronting the Chaplygin gas with data: background and perturbed cosmic dynamics

Phase space analysis and singularity classification for linearly interacting dark energy models

The Chaplygin gas as a model for modified teleparallel gravity?

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