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arXiv · 2208.06302

One-parameter dynamical dark-energy from the generalized Chaplygin gas

Rodrigo von Marttens·Dinorah Barbosa·Jailson Alcaniz
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Abstract

The fact that Einstein's equations connect the space-time geometry to the total matter content of the cosmic substratum, but not to individual contributions of the matter species, can be translated into a degeneracy in the cosmological dark sector. Such degeneracy makes it impossible to distinguish cases where dark energy (DE) interacts with dark matter (DM) from a dynamical non-interacting scenario using observational data based only on time or distance measurements. In this paper, based on the non-adiabatic generalized Chaplygin gas (gCg) model, we derive and study some cosmological consequences of a varying one-parameter dynamical DE parameterization, which does not allow phantom crossing. We perform a parameter selection using the most recent public available data, such as the data from Planck 2018, eBOSS DR16, Pantheon and KiDS-1000. We find that current observations provide strong constraints on the model parameters, leading to values very close to the $\Lambda$CDM cosmology, at the same time that the well-known $\sigma_8$ tension is reduced from $\sim 3\sigma$ to $\sim 1\sigma$ level.

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Rodrigo von Marttens, Dinorah Barbosa, Jailson Alcaniz. 2022-08-12. One-parameter dynamical dark-energy from the generalized Chaplygin gas. https://doi.org/10.1088/1475-7516%2F2023%2F04%2F052

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