Thermodynamic constraints and observational validation of the deceleration parameter

In this work, we propose a two-parameter parametrization for the deceleration parameter q(z) grounded in thermodynamic constraints and applied it to explore the evolution of the universe. The second law of thermodynamics imposes essential conditions to ensure that the system approaches equilibrium i...

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Main Authors: Y. Myrzakulov, O. Donmez, M. Koussour, S. Muminov, A. Dauletov, J. Rayimbaev
Format: Article
Language:English
Published: Elsevier 2025-07-01
Series:Nuclear Physics B
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Online Access:http://www.sciencedirect.com/science/article/pii/S0550321325001257
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author Y. Myrzakulov
O. Donmez
M. Koussour
S. Muminov
A. Dauletov
J. Rayimbaev
author_facet Y. Myrzakulov
O. Donmez
M. Koussour
S. Muminov
A. Dauletov
J. Rayimbaev
author_sort Y. Myrzakulov
collection DOAJ
description In this work, we propose a two-parameter parametrization for the deceleration parameter q(z) grounded in thermodynamic constraints and applied it to explore the evolution of the universe. The second law of thermodynamics imposes essential conditions to ensure that the system approaches equilibrium in late times, requiring q(z)≥−1 and dqdz>0 as z→−1. These constraints ensure that entropy does not decrease, stabilize the system, and facilitate a smooth transition from deceleration to acceleration, consistent with the observed cosmic expansion. Furthermore, the model avoids the phantom regime (ω<−1), preventing catastrophic future scenarios such as the Big Rip. Using the combined CC, Pantheon, SH0ES, and BAO datasets, we constrain the model parameters and compare the results with the standard ΛCDM model. Our findings indicate H0=70.82±0.88, with a transition redshift of zt=0.597±0.214, suggesting an earlier onset of acceleration compared to ΛCDM. The present deceleration parameter, q0=−0.364±0.032, implies a weaker acceleration than in ΛCDM. Moreover, we analyze the evolution of total energy density, pressure, and the effective equation of state parameter, confirming a quintessence-like behavior with ω0=−0.570±0.056. Our results provide a thermodynamically consistent framework for cosmic expansion, supporting a dark-energy-driven acceleration.
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spelling doaj-art-a7883815321a4200bc274d6859d9e7702025-08-20T02:28:19ZengElsevierNuclear Physics B0550-32132025-07-01101611691610.1016/j.nuclphysb.2025.116916Thermodynamic constraints and observational validation of the deceleration parameterY. Myrzakulov0O. Donmez1M. Koussour2S. Muminov3A. Dauletov4J. Rayimbaev5Department of General &amp; Theoretical Physics, L.N. Gumilyov Eurasian National University, Astana, 010008, KazakhstanCollege of Engineering and Technology, American University of the Middle East, Egaila 54200, KuwaitDepartment of Physics, University of Hassan II Casablanca, Morocco; Corresponding author.Mamun University, Bolkhovuz Street 2, Khiva 220900, UzbekistanDepartment of Digital Technologies, Alfraganus University, Yukori Karakamish Street 2a, Tashkent 100190, UzbekistanNew Uzbekistan University, Movarounnahr Street 1, Tashkent 100007, Uzbekistan; Urgench State University, Kh. Alimjan Str. 14, Urgench 221100, UzbekistanIn this work, we propose a two-parameter parametrization for the deceleration parameter q(z) grounded in thermodynamic constraints and applied it to explore the evolution of the universe. The second law of thermodynamics imposes essential conditions to ensure that the system approaches equilibrium in late times, requiring q(z)≥−1 and dqdz>0 as z→−1. These constraints ensure that entropy does not decrease, stabilize the system, and facilitate a smooth transition from deceleration to acceleration, consistent with the observed cosmic expansion. Furthermore, the model avoids the phantom regime (ω<−1), preventing catastrophic future scenarios such as the Big Rip. Using the combined CC, Pantheon, SH0ES, and BAO datasets, we constrain the model parameters and compare the results with the standard ΛCDM model. Our findings indicate H0=70.82±0.88, with a transition redshift of zt=0.597±0.214, suggesting an earlier onset of acceleration compared to ΛCDM. The present deceleration parameter, q0=−0.364±0.032, implies a weaker acceleration than in ΛCDM. Moreover, we analyze the evolution of total energy density, pressure, and the effective equation of state parameter, confirming a quintessence-like behavior with ω0=−0.570±0.056. Our results provide a thermodynamically consistent framework for cosmic expansion, supporting a dark-energy-driven acceleration.http://www.sciencedirect.com/science/article/pii/S0550321325001257Deceleration parameterThermodynamic constraintsDark energyEquation of state parameterObservational cosmology
spellingShingle Y. Myrzakulov
O. Donmez
M. Koussour
S. Muminov
A. Dauletov
J. Rayimbaev
Thermodynamic constraints and observational validation of the deceleration parameter
Nuclear Physics B
Deceleration parameter
Thermodynamic constraints
Dark energy
Equation of state parameter
Observational cosmology
title Thermodynamic constraints and observational validation of the deceleration parameter
title_full Thermodynamic constraints and observational validation of the deceleration parameter
title_fullStr Thermodynamic constraints and observational validation of the deceleration parameter
title_full_unstemmed Thermodynamic constraints and observational validation of the deceleration parameter
title_short Thermodynamic constraints and observational validation of the deceleration parameter
title_sort thermodynamic constraints and observational validation of the deceleration parameter
topic Deceleration parameter
Thermodynamic constraints
Dark energy
Equation of state parameter
Observational cosmology
url http://www.sciencedirect.com/science/article/pii/S0550321325001257
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AT adauletov thermodynamicconstraintsandobservationalvalidationofthedecelerationparameter
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