Barrow agegraphic dark energy

Sharma, Umesh Kumar; Varshney, Gunjan; Dubey, Vipin Chandra

doi:10.1142/s0218271821500218

Cited by 56 publications

(10 citation statements)

References 16 publications

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“…This entropy model has later been considered as a model for holographic dark energy [387,388] (see also Refs. [389][390][391][392][393][394][395][396][397][398][399][400][401][402][403][404][405][406][407][408]). In the toy model considered, a three-dimensional FIG.…”

Section: T Barrow Entropy Modifications To the Schwarzschild Metricmentioning

confidence: 99%

Horizon-scale tests of gravity theories and fundamental physics from the Event Horizon Telescope image of Sagittarius A$^*$

Vagnozzi¹,

Roy²,

Tsai³

et al. 2022

Preprint

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Horizon-scale images of black holes (BHs) and their shadows have opened an unprecedented window onto tests of gravity and fundamental physics in the strong-field regime, allowing us to test whether the Kerr metric provides a good description of the space-time in the vicinity of the event horizons of supermassive BHs. We consider a wide range of well-motivated deviations from classical General Relativity solutions, and constrain them using the Event Horizon Telescope (EHT) observations of Sagittarius A * (SgrA * ), connecting the size of the bright ring of emission to that of the underlying BH shadow and exploiting high-precision measurements of SgrA * 's mass-to-distance ratio. The scenarios we consider, and whose fundamental parameters we constrain, include various regular BH models, string-and non-linear electrodynamics-inspired space-times, scalar field-driven violations of the no-hair theorem, alternative theories of gravity, new ingredients such as the generalized uncertainty principle and Barrow entropy, and BH mimickers including examples of wormholes and naked singularities. We demonstrate that SgrA * 's image places particularly stringent constraints on models predicting a shadow size which is larger than that of a Schwarzschild BH of a given mass: for instance, in the case of Barrow entropy we derive constraints which are significantly tighter than the cosmological ones. Our results are among the first tests of fundamental physics from the shadow of SgrA * and, while the latter appears to be in excellent agreement with the predictions of General Relativity, we have shown that various well-motivated alternative scenarios (including BH mimickers) are far from being ruled out at present.

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Section: T Barrow Entropy Modifications To the Schwarzschild Metricmentioning

confidence: 99%

Horizon-scale tests of gravity theories and fundamental physics from the Event Horizon Telescope image of Sagittarius A$^*$

Vagnozzi¹,

Roy²,

Tsai³

et al. 2022

Preprint

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show abstract

“…Hence, such a complex structure leads to a modification of the black hole entropy. This idea may have interesting consequences in cosmological and holographic applications [69][70][71][72][73][74][75][76][77][78][79][80]. Nevertheless, it also has interesting implications on the black hole properties itself, since it changes the black hole temperature too [81][82][83].…”

Section: Introductionmentioning

confidence: 99%

Constraints on Barrow Entropy from M87* and S2 Star Observations

et al. 2022

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We use data from M87* central black hole shadow, as well as from the S2 star observations, in order to extract constraints on Barrow entropy. The latter is a modified entropy arising from quantum-gravitational effects on the black hole horizon, quantified by the new parameter Δ. Such a change in entropy leads to a change in temperature, as well as to the properties of the black hole and its shadow. We investigate the photon sphere and the shadow of a black hole with Barrow entropy, and assuming a simple model for infalling and radiating gas we estimate the corresponding intensity. Furthermore, we use the radius in order to extract the real part of the quasinormal modes, and for completeness we investigate the spherical accretion of matter onto the black hole, focusing on isothermal and polytropic test fluids. We extract the allowed parameter region, and by applying a Monte-Carlo-Markov Chains analysis we find that Δ≃0.0036−0.0145+0.0792. Hence, our results place the upper bound Δ≲0.0828 at 1σ, a constraint that is less strong than the Big Bang Nucleosynthesis one, but significantly stronger than the late-time cosmological constraints.

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“…It is worth mentioning the conventional quantum-corrected entropy with logarithmic corrections; though it simulates non-extensive Tsallis entropy, however, the physical principle and the intricate foundation are absolutely different. Thus, the purpose of this modified entropy relation just as the basis of HDE gives rise to BHDE [ 46 ], which is managed to improve phenomenology, and differentiating it from the standard framework of HDE [ 62 – 65 ]. The Barrow entropy expression is defined as [ 46 ] where is the Planck mass, is a dimensionless constant, and represents the IR cutoff.…”

Section: Warm Inflation Using Barrow Holographic Dark Energy Within R...mentioning

confidence: 99%

An exact solution approach to warm inflation using Tsallis and Barrow holographic dark energy entropy within Rastall gravity

2022

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This paper studies the phenomena of warm inflation in a modified cosmological scenario within Rastall gravity. In this context, we modify the standard Friedmann equations using recently proposed Tsallis and Barrow holographic dark energy entropies, alternatively. For both entropies, the exact solutions including the inflaton field, potential required to produce inflation and the scale factor are obtained under slow-roll approximation for low- and high-dissipative regimes. We obtain exponentially growing scale factors for both dark energy models. To confront the theoretical predictions of these models with recent observational data, we calculate the slow-roll parameters, number of e-folds, scalar spectral index, running of scalar spectral index and the tensor-to-scalar ratio for both extremes of dissipation. The Planck bounds on inflationary trajectories are being used to constraint the free parameters. The results are interesting and physically viable up to 2 level.

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Barrow agegraphic dark energy

Cited by 56 publications

References 16 publications

Horizon-scale tests of gravity theories and fundamental physics from the Event Horizon Telescope image of Sagittarius A$^*$

Horizon-scale tests of gravity theories and fundamental physics from the Event Horizon Telescope image of Sagittarius A$^*$

Constraints on Barrow Entropy from M87* and S2 Star Observations

An exact solution approach to warm inflation using Tsallis and Barrow holographic dark energy entropy within Rastall gravity

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