6–10 Jul 2026
University of the Western Cape
Africa/Johannesburg timezone
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Joint cosmological constraints on interacting vacuum energy models

7 Jul 2026, 11:40
20m
Lecture Hall C5 (University of the Western Cape)

Lecture Hall C5

University of the Western Cape

Oral Presentation Track D - Astrophysics & Space Science Astrophysics & Space Science

Speaker

Olebogeng Tlhapane (Centre for Space Research, North-West University)

Description

We examine interacting vacuum energy (IVE) models involving energy transfer between vacuum energy and cold dark matter, such as: $(i)\ Q = \iota HV$, $(ii)\ Q = \xi H\rho_c$, and $(iii)\ Q=3\eta H\frac{V\rho_c}{\rho_c+V}$ with the aim of addressing the cosmological tensions: $H_0$ and $\sigma_8$. To assess the cosmological viability of these IVE models, we constrain their dynamics through a joint analysis of late-time cosmological observations, including Cosmic chronometers, Baryon acoustic oscillations, PantheonP+SHOES, and Redshift-space distortion $(f_{\sigma_8})$ dat asets. We conducted a statistical analysis using a newly developed Markov Chain Monte Carlo (MCMC) simulation called Kosmulator to find the best-fit values of $\Omega_m$, $H_0$, and $\sigma_8$, along with the coupling parameters: $\iota, \xi, \text{and}\hspace{1mm} \eta$. Additionally, we used Akaike Information Criterion $(AIC)$ and Bayesian Information Criterion $(BIC)$ criteria to evaluate deviations from the $\Lambda$CDM framework.

Keywords: Cosmological tensions, Vacuum energy, Cold dark matter

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Author

Olebogeng Tlhapane (Centre for Space Research, North-West University)

Co-authors

Presentation materials

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