Kinematic Reconstruction of $Λ(t)$CDM Models
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arXiv
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2025
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| author | Guillen, P. A. S. Jesus, J. F. Valentim, R. |
| author_facet | Guillen, P. A. S. Jesus, J. F. Valentim, R. |
| contents | In this work, we have \textbf{analysed} two kinematic parametrizations for $Λ(t)$CDM models, namely, the linear expansions $Λ(z)=Λ_0+Λ_1z$ and $Q(z)=Q_0+Q_1z$, where $Q$ is the interaction term. In the case of the $Q(z)$ parametrization, we have also tested the particular case of a constant interaction term, $Q(z)=Q_0$. In order to constrain the free parameters of these models, we have used Cosmic Chronometers (CC), SNe Ia data (Pantheon+\&SH0ES) and BAO data. As a general result, we have found weak constraints over the free parameters of the analysed models. In the case of $Λ(z)$, we have found for the $Λ$ variation parameter, $Ω_{\Lambda1}\equiv\frac{Λ_1}{3H_0^2}=0.02\pm0.14$. In the case of the $Q(z)$ parametrization, we have worked with the dimensionless interaction term $\gQ(z)\equiv\frac{8πGQ(z)}{3H_0^3}$, from which we have found $\gQ_0 = 2.2 \pm 2.7$ and $\gQ_1 = -6.2 \pm 7.6$. In the particular case of a constant interaction term, we have found $\gQ_0 = 0.18 \pm 0.7$. All these constraints are at 68\% c.l. The constraints we have obtained are compatible with the standard $Λ$CDM model, although still providing a large margin for $Λ$ variation. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2512_14578 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Kinematic Reconstruction of $Λ(t)$CDM Models Guillen, P. A. S. Jesus, J. F. Valentim, R. Cosmology and Nongalactic Astrophysics In this work, we have \textbf{analysed} two kinematic parametrizations for $Λ(t)$CDM models, namely, the linear expansions $Λ(z)=Λ_0+Λ_1z$ and $Q(z)=Q_0+Q_1z$, where $Q$ is the interaction term. In the case of the $Q(z)$ parametrization, we have also tested the particular case of a constant interaction term, $Q(z)=Q_0$. In order to constrain the free parameters of these models, we have used Cosmic Chronometers (CC), SNe Ia data (Pantheon+\&SH0ES) and BAO data. As a general result, we have found weak constraints over the free parameters of the analysed models. In the case of $Λ(z)$, we have found for the $Λ$ variation parameter, $Ω_{\Lambda1}\equiv\frac{Λ_1}{3H_0^2}=0.02\pm0.14$. In the case of the $Q(z)$ parametrization, we have worked with the dimensionless interaction term $\gQ(z)\equiv\frac{8πGQ(z)}{3H_0^3}$, from which we have found $\gQ_0 = 2.2 \pm 2.7$ and $\gQ_1 = -6.2 \pm 7.6$. In the particular case of a constant interaction term, we have found $\gQ_0 = 0.18 \pm 0.7$. All these constraints are at 68\% c.l. The constraints we have obtained are compatible with the standard $Λ$CDM model, although still providing a large margin for $Λ$ variation. |
| title | Kinematic Reconstruction of $Λ(t)$CDM Models |
| topic | Cosmology and Nongalactic Astrophysics |
| url | https://arxiv.org/abs/2512.14578 |