Modified cosmology through Kaniadakis horizon entropy

Lymperis, Andreas; Basilakos, Spyros; Saridakis, Emmanuel N.

doi:10.1140/epjc/s10052-021-09852-9

Cited by 43 publications

(23 citation statements)

References 76 publications

(109 reference statements)

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“…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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Section: Introductionmentioning

confidence: 99%

Constraints on Barrow Entropy from M87* and S2 Star Observations

et al. 2022

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“…However, several extensions have appeared in the literature, by using various modified entropy relations, arising from nonextensive generalizations of the statistics of horizon degrees of freedom and/or quantum gravitational deformations of the horizon geometry. Among these, special focus has been placed on Tsallis [19] and Kaniadakis [20] entropies, whose cosmological applications have been addressed in [21][22][23][24][25][26][27][28][29][30][31][32].…”

Section: Introductionmentioning

confidence: 99%

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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“…For example, a largely used statistics is that introduced by Kaniadakis, which comes from relativistic corrections to the Boltzmann theory [108]. It would be interesting to explore how modified Friedmann equations affect the mass density/pressure content of the Universe in that context [109]. Along this line, preliminary consid-erations could be derived by making use of the relation between Tsallis and Kaniadakis entropic measures [110].…”

Section: Connecting Tsallis Thermostatistics and Generalized Uncertai...mentioning

confidence: 99%

Baryogenesis in non-extensive Tsallis Cosmology

Luciano¹,

Giné²

2022

Preprint

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Non-extensive Tsallis thermostatistics is a widespread paradigm to describe large-scale gravitational systems. In this work we use Tsallis Cosmology to study thermodynamic gravity and derive modified Friedmann equations. We show that corrections induced by non-extensivity affect the Hubble function evolution during the radiation-dominated epoch. In turn, this leads to non-trivial modifications of the mass density and pressure content of the Universe, which provide a viable mechanism allowing for baryogenesis, even in the presence of the standard interaction between the Ricci scalar and baryon current. By demanding consistency with current observational bounds on baryogenesis, we constrain Tsallis δ parameter to be |δ − 1| 10 −3 . Based on the recently established connection between Tsallis thermostatistics and the quantum gravitational generalization of the uncertainty principle at Planck scale (GUP), we finally show that this bound is in agreement with the estimation of the GUP parameter predicted by many quantum gravity models.

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Modified cosmology through Kaniadakis horizon entropy

Cited by 43 publications

References 76 publications

Constraints on Barrow Entropy from M87* and S2 Star Observations

Constraints on Barrow Entropy from M87* and S2 Star Observations

Baryon asymmetry from Barrow entropy: theoretical predictions and observational constraints

Baryogenesis in non-extensive Tsallis Cosmology

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