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arXiv · 2308.01200

Alleviating both $H_0$ and $\sigma_8$ tensions in Tsallis cosmology

Spyros Basilakos·Andreas Lymperis·Maria Petronikolou·Emmanuel N. Saridakis
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Abstract

We present how Tsallis cosmology can alleviate both $H_0$ and $\sigma_8$ tensions simultaneously. Such a modified cosmological scenario is obtained by the application of the gravity-thermodynamics conjecture, but using the non-additive Tsallis entropy, instead of the standard Bekenstein-Hawking one. Hence, one obtains modified Friedmann equations, with extra terms that depend on the new Tsallis exponent $\delta$ that quantifies the departure from standard entropy. We show that for particular $\delta$ choices we can obtain a phantom effective dark energy, which is known to be one of the sufficient mechanisms that can alleviate $H_0$ tension. Additionally, for the same parameter choice we obtain an increased friction term and an effective Newton's constant smaller than the usual one, and thus the $\sigma_8$ tension is also solved. These features act as a significant advantage of Tsallis modified cosmology.

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Spyros Basilakos, Andreas Lymperis, Maria Petronikolou, Emmanuel N. Saridakis. 2023-08-02. Alleviating both $H_0$ and $\sigma_8$ tensions in Tsallis cosmology. https://doi.org/10.1140/epjc%2Fs10052-024-12573-4

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