Cosmological constraints on bulk viscous f(Q,T) gravity

Sokoliuk, Oleksii; Baransky, Alexander

doi:10.1002/asna.20220003

Cited by 16 publications

(10 citation statements)

References 118 publications

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“…The model does not exhibit a late time acceleration for zero or [72]). OHD corresponds to the Observational Hubble Data set with 57 entries [73] large positive values of 𝜆. However, similar to Moradpour et al's results, we get a late time acceleration for negative values of 𝜆, which could explain the observation.…”

Section: Standard Rényi Hde and Its Inconsistenciessupporting

confidence: 88%

“…Hubble parameter (𝐻 (𝑧)) as a function of redshift (𝑧) for different values of 𝜆 with standard Rényi HDE density (with Ω 𝑚0 = 0.315 and 𝐻 0 = 67.4 km/s/Mpc[72]). OHD corresponds to the Observational Hubble Data set with 57 entries[73]…”

mentioning

confidence: 99%

“…(a) Hubble parameter 𝐻 (𝑧) and (b) apparent magnitude 𝑚(𝑧) of Type-1a supernovae as a function of redshift (𝑧) for different values of 𝜆.Here we took 𝑀 = −19.366 as the nuisance parameter[76] to estimate the apparent magnitude (with Ω 𝑚0 = 0.315 and 𝐻 0 = 67.4 km/s/Mpc[72]). Observational Hubble Data from[73] and Pantheon data from[77]. (We use large values of 𝜆 only to highlight the deviation.…”

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confidence: 99%

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Holographic dark energy from the laws of thermodynamics with Rényi entropy

Manosh¹,

Shaji²,

Mathew³

2022

Preprint

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This article investigates the relationship between the holographic principle and the laws of thermodynamics in explaining the late-time acceleration of the universe. First, we explore the possibilities of generating the standard holographic dark energy (SHDE) from the laws of horizon thermodynamics. Except for entropies that follow an exponent stretched area law, unless we redefine the horizon temperature, we found it challenging to construct a one-to-one correspondence between the dark energies defined by the holographic principle and the laws of thermodynamics. Secondly, in SHDE models, unless we invoke some phenomenological interactions, it is impossible to explain the late-time cosmic acceleration with the Hubble horizon as the IR cutoff. On the other hand, it is possible to induce dark energy as an integration constant using the laws of thermodynamics on the Hubble horizon. These motivated us to explore a feasible way to invoke the holographic principle from the laws of horizon thermodynamics. We show that the additional terms that appear in the modified Friedmann equations on using entropies other than the Bekenstein-Hawking entropy in the first law of thermodynamics can behave like a dynamic holographic dark energy (HDE). We study the features of such an HDE with Rényi entropy as the choice without considering any non-standard interactions. Interestingly, the resulting form of dark energy reduces to the standard cosmological constant when Rényi entropy reduces to the Bekenstein-Hawking entropy. By examining different parameters, we affirm the validity of our approach to dark energy, which respects both holographic principle and thermodynamics.

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Section: Standard Rényi Hde and Its Inconsistenciessupporting

confidence: 88%

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confidence: 99%

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confidence: 99%

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Holographic dark energy from the laws of thermodynamics with Rényi entropy

Manosh¹,

Shaji²,

Mathew³

2022

Preprint

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“…Note that the resulting theory differs from well-known f (R, T) gravity [25] and f (T, T ) gravity [26] in that it is a novel modified gravitational theory based on a more general geometric framework than Riemannian geometry (Weyl geometry), with no curvature-equivalent and no torsion-equivalent, and its cosmological implications are very interesting. In the literature, there are active works in the framework f (Q, T) gravity theory [27][28][29][30][31]. Thus, there is a motivation to examine several theoretical, observational and cosmological aspects of f (Q, T) gravity.…”

Section: Introductionmentioning

confidence: 99%

Quintessence Universe and cosmic acceleration in f (Q, T) gravity

Koussour

Myrzakulov

Shekh

et al. 2022

Int. J. Mod. Phys. D

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The problem of cosmic acceleration and dark energy is one of the mysteries presently posed in the scientific society that general relativity has not been able to solve. In this work, we have considered alternative models to explain this late-time acceleration in a flat Friedmann-Lemaitre-Robertson-Walker (FLRW) Universe within the framework of the f (Q, T) modified gravity theory (where Q is the non-metricity and T is the trace of the energy-momentum tensor) recently proposed by Xu et al. (Eur. Phys. J. C 79 (2019) 708), which is an extension of f (Q) gravity with the addition of the T term. Here, we presume a specific form of f (Q, T) = αQ + βQ 2 + γT where α, β and γ are free model parameters, and obtained the exact solutions by assuming the cosmic time-redshift relation as t(z) = nt 0 m g(z) which produces the Hubble parameter of the form H(z) = mH 0 m+n 1 g(z) + 1 where m and n are the non-negative constants, we find the best values for them using 57 data points of the Hubble parameter H (z). Also, we find the behavior of different cosmological parameters as the deceleration parameter q , energy density ρ , pressure p and EoS parameter (ω) and compare them with the observational results. To ensure the validity of the results, we studied the energy conditions along with jerk parameter. Finally, we found that our model behaves similarly to the quintessence Universe.

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“…f (Q, T ) gravity has been deeply studied recently. The Chaplygin gas in the context of f (Q, T ) was explored in [18], observational constraints of f (Q, T ) gravity functions are presented in [19][20][21][22][23][24][25][26][27][28][29] and the linear theory of cosmological perturbations were explored in [30]. In addition to this, it has been shown that a particular quadratic function on…”

Section: Introductionmentioning

confidence: 99%

Effects of the matter Lagrangian degeneracy in $f(Q,T)$ gravity

Nájera,

Alvarado

2022

Preprint

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In this paper, we investigated the theoretical and cosmological effects of the matter Lagrangian degeneracy in an extension of the Symmetric Teleparallel Equivalent of General Relativity, denoted as f (Q, T ) gravity. This degeneracy comes from the fact that both Lm = p and Lm = −ρ can give rise to the stress-energy tensor of a perfect fluid. The f (Q, T ) equations depend on the form of the matter Lagrangian and hence they also have a degeneracy that has influence on the density evolution of dust matter and radiation, on the form of the generalized Friedmann equations and also shows changes in the cosmological parameters confidence regions when performing Monte Carlo Markov Chains analyses. Our results suggest that since changing the matter Lagrangian causes different theoretical and cosmological results, future studies in f (Q, T ) gravity should consider both forms of the matter Lagrangians to account for the different mathematical and observational results.

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Cosmological constraints on bulk viscous f(Q,T) gravity

Cited by 16 publications

References 118 publications

Holographic dark energy from the laws of thermodynamics with Rényi entropy

Holographic dark energy from the laws of thermodynamics with Rényi entropy

Quintessence Universe and cosmic acceleration in f (Q, T) gravity

Effects of the matter Lagrangian degeneracy in $f(Q,T)$ gravity

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