Barrow Entropy Cosmology: an observational approach with a hint of stability analysis

León, Genly; Magaña, Juan; Hernández-Almada, A.; García‐Aspeitia, Miguel A.; Verdugo, T.; Motta, V.

doi:10.1088/1475-7516/2021/12/032

Cited by 43 publications

(19 citation statements)

References 58 publications

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“…∆. In particular, we find the upper limit ∆ 0.001 at 1σ, tighter than cosmological constraints requiring ∆ 0.1888 [409,410], but weaker than Big Bang Nucleosynthesis constraints requiring ∆ 1.4 × 10 −4 [411]. At 2σ, we have the weaker constraint ∆ 0.035, which is nonetheless still stronger than the cosmological one.…”

Section: T Barrow Entropy Modifications To the Schwarzschild Metriccontrasting

confidence: 61%

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 Metriccontrasting

confidence: 61%

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

“…Additionally, one can apply Barrow entropy to the holographic principle, obtaining Barrow holographic dark energy [35][36][37][38][39]. Hence, one can confront the above constructions with observational data end amongst others extract constraints on the Barrow exponent [40][41][42][43]. As expected, in all these studies deviations from the BH entropy are found to be relatively small.…”

Section: Introductionmentioning

confidence: 58%

Baryon asymmetry from Barrow entropy: theoretical predictions and observational constraints

Luciano

Saridakis

2022

Eur. Phys. J. C

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We investigate the generation of baryon asymmetry from the corrections brought about in the Friedman equations due to Barrow entropy. In particular, by applying the gravity-thermodynamics conjecture one obtains extra terms in the Friedmann equations that change the Hubble function evolution during the radiation-dominated epoch. Hence, even in the case of standard coupling between the Ricci scalar and baryon current they can lead to a non-zero baryon asymmetry. In order to match observations we find that the Barrow exponent should lie in the interval $$0.005\lesssim \Delta \lesssim 0.008$$ 0.005 ≲ Δ ≲ 0.008 , which corresponds to a slight deviation from the standard Bekenstein–Hawking entropy. The upper bound is tighter than the one of other observational constraints, however the interesting feature is that in the present analysis we obtain a non-zero lower bound. Nevertheless this lower bound would disappear if the baryon asymmetry in Barrow-modified cosmology is generated by other mechanisms, not related to the Barrow modification.

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“…( 2), in line with most literature. Cosmological and black hole shadow constraints (assuming a fixed δ) has put an upper bound on δ, which is typically δ O(10 −3 ) or O(10 −4 ) [4][5][6][7][8][9].…”

Section: Introduction: Barrow Entropy and Quantum Gravitymentioning

confidence: 99%

Sign Switching Dark Energy from a Running Barrow Entropy

Di Gennaro,

Ong

2022

Preprint

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Barrow Entropy Cosmology: an observational approach with a hint of stability analysis

Cited by 43 publications

References 58 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$^*$

Baryon asymmetry from Barrow entropy: theoretical predictions and observational constraints

Sign Switching Dark Energy from a Running Barrow Entropy

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