Bulk viscous matter interacting with decaying vacuum energy density: a model for late-time evolution of the Universe
Abstract The late-time cosmological expansion within a flat Friedmann–Lemaître–Robertson–Walker (FLRW) spacetime is studied using a model characterized by bulk viscous dark matter (bulk viscosity $$\zeta = \zeta _0 \rho _m H^{-1}+\zeta _1 H $$ ζ = ζ 0 ρ m H - 1 + ζ 1 H , $$\zeta _0$$ ζ 0 & $$\ze...
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SpringerOpen
2025-07-01
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| Series: | European Physical Journal C: Particles and Fields |
| Online Access: | https://doi.org/10.1140/epjc/s10052-025-14500-7 |
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| author | Tanmay Nandi Amitava Choudhuri |
| author_facet | Tanmay Nandi Amitava Choudhuri |
| author_sort | Tanmay Nandi |
| collection | DOAJ |
| description | Abstract The late-time cosmological expansion within a flat Friedmann–Lemaître–Robertson–Walker (FLRW) spacetime is studied using a model characterized by bulk viscous dark matter (bulk viscosity $$\zeta = \zeta _0 \rho _m H^{-1}+\zeta _1 H $$ ζ = ζ 0 ρ m H - 1 + ζ 1 H , $$\zeta _0$$ ζ 0 & $$\zeta _1$$ ζ 1 are constants, and H, the Hubble parameter) interacting with a decaying vacuum density $$\rho _{\Lambda } = \mathcal {C}_0 + 3\nu H^2$$ ρ Λ = C 0 + 3 ν H 2 , where $$\mathcal {C}_0$$ C 0 and $$\nu $$ ν are constants. The bulk viscous pressure is described by Eckart’s theory. The interaction term is defined as $$ Q=3H\alpha (\rho _m+\rho _\Lambda )$$ Q = 3 H α ( ρ m + ρ Λ ) , where $$\alpha $$ α , the interaction parameter. Analytical solutions for the Hubble parameter and the scale factor have been derived. The validity of the models is evaluated by constraining their free parameters using observational data from Cosmic Chronometer, the Pantheon, and a combination of both datasets. The goodness of fit is assessed by minimizing the $$\chi ^2$$ χ 2 function utilizing the Markov Chain Monte Carlo (MCMC) method. Selection information criteria, namely AIC and BIC, have been obtained to analyze the models’ stability. Additionally, several essential cosmological parameters characterizing the evolution dynamics are estimated and discussed analytically, and compared with the $$\Lambda $$ Λ CDM model. The proposed model suggests a transition from the deceleration to the acceleration phase, indicating thermodynamic equilibrium in the distant future, aligning with the $$\Lambda $$ Λ CDM model. The model shows a slight deviation from $$\Lambda $$ Λ CDM model and effectively reduces the $$H_0$$ H 0 tension between local measurements by R21 and global measurements by Planck 2018. The model is consistent with thermodynamic laws and upholds the second law of thermodynamics. Finally, Phase-space analysis supports the same evolutionary transitional phases. |
| format | Article |
| id | doaj-art-e74e4b2a719b443db50b8fb18bcda58f |
| institution | Kabale University |
| issn | 1434-6052 |
| language | English |
| publishDate | 2025-07-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | European Physical Journal C: Particles and Fields |
| spelling | doaj-art-e74e4b2a719b443db50b8fb18bcda58f2025-08-20T04:03:06ZengSpringerOpenEuropean Physical Journal C: Particles and Fields1434-60522025-07-0185712110.1140/epjc/s10052-025-14500-7Bulk viscous matter interacting with decaying vacuum energy density: a model for late-time evolution of the UniverseTanmay Nandi0Amitava Choudhuri1Department of Physics, The University of BurdwanDepartment of Physics, The University of BurdwanAbstract The late-time cosmological expansion within a flat Friedmann–Lemaître–Robertson–Walker (FLRW) spacetime is studied using a model characterized by bulk viscous dark matter (bulk viscosity $$\zeta = \zeta _0 \rho _m H^{-1}+\zeta _1 H $$ ζ = ζ 0 ρ m H - 1 + ζ 1 H , $$\zeta _0$$ ζ 0 & $$\zeta _1$$ ζ 1 are constants, and H, the Hubble parameter) interacting with a decaying vacuum density $$\rho _{\Lambda } = \mathcal {C}_0 + 3\nu H^2$$ ρ Λ = C 0 + 3 ν H 2 , where $$\mathcal {C}_0$$ C 0 and $$\nu $$ ν are constants. The bulk viscous pressure is described by Eckart’s theory. The interaction term is defined as $$ Q=3H\alpha (\rho _m+\rho _\Lambda )$$ Q = 3 H α ( ρ m + ρ Λ ) , where $$\alpha $$ α , the interaction parameter. Analytical solutions for the Hubble parameter and the scale factor have been derived. The validity of the models is evaluated by constraining their free parameters using observational data from Cosmic Chronometer, the Pantheon, and a combination of both datasets. The goodness of fit is assessed by minimizing the $$\chi ^2$$ χ 2 function utilizing the Markov Chain Monte Carlo (MCMC) method. Selection information criteria, namely AIC and BIC, have been obtained to analyze the models’ stability. Additionally, several essential cosmological parameters characterizing the evolution dynamics are estimated and discussed analytically, and compared with the $$\Lambda $$ Λ CDM model. The proposed model suggests a transition from the deceleration to the acceleration phase, indicating thermodynamic equilibrium in the distant future, aligning with the $$\Lambda $$ Λ CDM model. The model shows a slight deviation from $$\Lambda $$ Λ CDM model and effectively reduces the $$H_0$$ H 0 tension between local measurements by R21 and global measurements by Planck 2018. The model is consistent with thermodynamic laws and upholds the second law of thermodynamics. Finally, Phase-space analysis supports the same evolutionary transitional phases.https://doi.org/10.1140/epjc/s10052-025-14500-7 |
| spellingShingle | Tanmay Nandi Amitava Choudhuri Bulk viscous matter interacting with decaying vacuum energy density: a model for late-time evolution of the Universe European Physical Journal C: Particles and Fields |
| title | Bulk viscous matter interacting with decaying vacuum energy density: a model for late-time evolution of the Universe |
| title_full | Bulk viscous matter interacting with decaying vacuum energy density: a model for late-time evolution of the Universe |
| title_fullStr | Bulk viscous matter interacting with decaying vacuum energy density: a model for late-time evolution of the Universe |
| title_full_unstemmed | Bulk viscous matter interacting with decaying vacuum energy density: a model for late-time evolution of the Universe |
| title_short | Bulk viscous matter interacting with decaying vacuum energy density: a model for late-time evolution of the Universe |
| title_sort | bulk viscous matter interacting with decaying vacuum energy density a model for late time evolution of the universe |
| url | https://doi.org/10.1140/epjc/s10052-025-14500-7 |
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