English

Modified cosmology from quantum deformed entropy

General Relativity and Quantum Cosmology 2023-09-25 v1 High Energy Physics - Theory

Abstract

In Ref. [S. Jalalzadeh, Phys. Lett. B 829 (2022) 137058], Jalalzadeh established that the thermodynamical entropy of a quantum-deformed black hole with horizon area AA can be written as Sq=πsin(A8GN)/sin(π2N)S_q=\pi\sin\left(\frac{A}{8G\mathcal N} \right)/\sin\left(\frac{\pi}{2\mathcal N} \right), where N=Lq2/LP2\mathcal N=L_q^2/L_\text{P}^2, LPL_\text{P} being the Planck length and LqL_q denoting, generically, the q-deformed cosmic event horizon distance LqL_q. Motivated by this, we now extend the framework constructed in [S. Jalalzadeh, Phys. Lett. B 829 (2022) 137058] towards the Friedmann and Raychaudhuri equations describing spatially homogeneous and isotropic universe dynamics. Our procedure in this paper involves a twofold assumption. On the one hand, we take the entropy associated with the apparent horizon of the Robertson-Walker universe in the form of the aforementioned expression. On the other hand, we assume that the unified first law of thermodynamics, dE=TdS+WdVdE=TdS+WdV, holds on the apparent horizon. Subsequently, we find a novel modified cosmological scenario characterized by quantum-deformed (q-deformed) Friedmann and Raychaudhuri equations containing additional components that generate an effective dark energy sector. Our results indicate an effective dark energy component, which can explain the Universe's late-time acceleration. Moreover, the Universe follows the standard thermal history, with a transition redshift from deceleration to acceleration at ztran=0.5z_\text{tran}=0.5. More precisely, according to our model, at a redshift of z=0.377z = 0.377, the effective dark energy dominates with a de Sitter universe in the long run. We include the evolution of luminosity distance, μ\mu, the Hubble parameter, H(z)H(z), and the deceleration parameter, q(z)q(z), versus redshift. Finally, we have conducted a comparative analysis of our proposed model with others involving non-extensive entropies.

Keywords

Cite

@article{arxiv.2308.12089,
  title  = {Modified cosmology from quantum deformed entropy},
  author = {S. Jalalzadeh and H. Moradpour and P. V. Moniz},
  journal= {arXiv preprint arXiv:2308.12089},
  year   = {2023}
}

Comments

16 pages, 8 figures, to appear in Physics of the Dark Universe

R2 v1 2026-06-28T12:02:26.844Z