Sign Switching Dark Energy from a Running Barrow Entropy

Di Gennaro, Sofia; Ong, Yen Chin

doi:10.48550/arxiv.2205.09311

Cited by 6 publications

(7 citation statements)

References 51 publications

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“…Cosmological implications of Barrow entropy have been recently studied in the context of Big Bang Nucleosynthesis [51] and Baryogenesis [52], among others. The possibility of a running ∆ has also been considered in [53].…”

Section: Barrow Holographic Dark Energymentioning

confidence: 99%

Inflation and tachyon model of Barrow holographic dark energy

Luciano¹,

Liu²

2022

Preprint

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We study the connection between the tachyon dark energy model and Barrow holographic dark energy (BHDE). The latter is a modified scenario based on the application of the holographic principle with Barrow entropy instead of the usual Bekenstein-Hawking one. We reconstruct the dynamics of the tachyon scalar field both in the presence and absence of interactions between dark energy and matter. For a flat Friedmann-Robertson-Walker Universe, it is shown that the time derivative of the tachyon field Ṫ 2 vanishes. This leads to the condition ωD = −1 for the equation of state parameter of BHDE, providing a potential explanation for the origin of the cosmological constant. On the other hand, the tachyon field exhibits a non-trivial dynamics for a non-flat Universe. In particular, in a closed Universe Ṫ 2 decreases monotonically for increasing cos(R h /a), where R h and a are the future event horizon and the scale factor. The same behavior occurs in an open Universe, but in this case Ṫ 2 < 0, revealing that BHDE cannot model the tachyon dark energy. We then study the inflation mechanism. We find an analytical solution for the characteristic slow-roll parameters, the scalar spectral index and the tensor-to-scalar ratio. We finally comment on the Trans-Planckian Censorship Conjecture in BHDE.

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Section: Barrow Holographic Dark Energymentioning

confidence: 99%

Inflation and tachyon model of Barrow holographic dark energy

Luciano¹,

Liu²

2022

Preprint

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“…This will modify the RHS of the field equation (i.e., give rise to an effective gravitational constant). In [18], it is argued why the Barrow index ∆ is expected to run, i.e., energy-scale dependent, but since ∆ is fixed over a given horizon, this does not affect the derivation of the field equation itself. The effective theory is incomplete in the sense that if ∆ does run, the dynamics of ∆ cannot be determined.…”

Section: Comment On the Hawking Ratementioning

confidence: 99%

How Barrow Entropy Modifies Gravity: With Comments on Tsallis Entropy

Gennaro¹,

Xu²,

Ong³

2022

Preprint

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Barrow proposed that the area law of the horizon entropy might receive a "fractal correction" S ∝ A 1+∆/2 due to quantum gravitational effects, with 0 ∆ 1 measures the deviation from the standard area law. While such a modification has been widely studied in the literature, its corresponding theory of gravity has not been discussed. We follow Jacobson's approach to derive the modified gravity theory, and find that in the stationary case the resulting theory only differs from general relativity by a re-scaled cosmological constant. Consequently in asymptotically flat stationary spacetimes the theory is identical to general relativity. The theory is not applicable when there is no horizon; the multi-horizon case is complicated. We also comment on the Hawking evaporation rate beyond the effective theory.

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“…We notice that the obtained estimation of Barrow parameter fits with the result ∆ = 0.094 +0.093 −0.101 derived in [26] and is very close to the constraint ∆ = 0.075 +0.001 −0.002 of [76], but it lies outside the intervals 0.005 ≤ ∆ ≤ 0.008 [32] and ∆ 1.4 × 10 −4 [28] found via baryogenesis and Big Bang Nucleosynthesis measurements, respectively. This discrepancy might be understood by assuming a HDE description of the Universe with a running Barrow entropy, as discussed in [77].…”

Section: B Interacting Modelmentioning

confidence: 99%

Cosmic evolution and thermal stability of Barrow holographic dark energy in nonflat Friedmann-Robertson-Walker Universe

Luciano¹

2022

Preprint

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We study the cosmological evolution of a nonflat Friedmann-Robertson-Walker Universe filled by pressureless dark matter and Barrow Holographic Dark Energy (BHDE). The latter is a dark energy model based on the holographic principle with Barrow entropy instead of the standard Bekenstein-Hawking one. By assuming the apparent horizon of the Universe as IR cutoff, we explore both the cases where a mutual interaction between the dark components of the cosmos is absent/present. We analyze the behavior of various model parameters, such as the BHDE density parameter, the equation of state parameter, the deceleration parameter, the jerk parameter and the square of sound speed. We also comment on the observational consistency of our predictions, showing that the interacting model turns out to be favored by recent experimental constraints from Planck+WP+BAO, SNIa+CMB+LSS and Union2 SNIa joint analysis over the non-interacting one. The thermal stability of our framework is finally discussed by demanding the positivity of the heat capacities and compressibilities of the cosmic fluid.

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Sign Switching Dark Energy from a Running Barrow Entropy

Cited by 6 publications

References 51 publications

Inflation and tachyon model of Barrow holographic dark energy

Inflation and tachyon model of Barrow holographic dark energy

How Barrow Entropy Modifies Gravity: With Comments on Tsallis Entropy

Cosmic evolution and thermal stability of Barrow holographic dark energy in nonflat Friedmann-Robertson-Walker Universe

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