Relaxing cosmological tensions with a sign switching cosmological constant: Improved results with Planck, BAO, and Pantheon data

Abstract

We present a further observational analysis of the ${\mathrm{\ensuremath{\Lambda}}}_{\mathrm{s}}\mathrm{CDM}$ model proposed in Akarsu et al. [Phys. Rev. D 104, 123512 (2021)]. This model is based on the recent conjecture suggesting the Universe has transitioned from anti--de Sitter vacua to de Sitter vacua (viz., the cosmological constant switches sign from negative to positive), at redshift ${z}_{\ifmmode\dagger\else\textdagger\fi{}}\ensuremath{\sim}2$, inspired by the graduated dark energy model proposed in Akarsu et al. [Phys. Rev. D 101, 063528 (2020)]. ${\mathrm{\ensuremath{\Lambda}}}_{\mathrm{s}}\mathrm{CDM}$ was previously claimed to simultaneously relax five cosmological discrepancies, namely, the ${H}_{0}$, ${S}_{8}$, and ${M}_{B}$ tensions along with the $\mathrm{Ly}\text{\ensuremath{-}}\ensuremath{\alpha}$ and ${\ensuremath{\omega}}_{\mathrm{b}}$ anomalies, which prevail within the standard $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$ model as well as its canonical/simple extensions. In the present work, we extend the previous analysis by constraining the model using the Pantheon data (with and without the SH0ES ${M}_{B}$ prior) and/or the completed BAO data along with the full Planck CMB data. We find that ${\mathrm{\ensuremath{\Lambda}}}_{\mathrm{s}}\mathrm{CDM}$ exhibits a better fit to the data compared to $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$, and simultaneously relaxes the six discrepancies of $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$, viz., the ${H}_{0}$, ${M}_{B}$, ${S}_{8}$, $\mathrm{Ly}\text{\ensuremath{-}}\ensuremath{\alpha}$, ${t}_{0}$, and ${\ensuremath{\omega}}_{\mathrm{b}}$ discrepancies, all of which are discussed in detail. When the ${M}_{B}$ prior is included in the analyses, ${\mathrm{\ensuremath{\Lambda}}}_{\mathrm{s}}\mathrm{CDM}$ performs significantly better in relaxing the ${H}_{0}$, ${M}_{B}$, and ${S}_{8}$ tensions with the constraint ${z}_{\ifmmode\dagger\else\textdagger\fi{}}\ensuremath{\sim}1.8$ even when the $\mathrm{Ly}\text{\ensuremath{-}}\ensuremath{\alpha}$ data (which imposed the ${z}_{\ifmmode\dagger\else\textdagger\fi{}}\ensuremath{\sim}2$ constraint in the previous studies) are excluded. In contrast, the presence of the ${M}_{B}$ prior causes only negligible improvements for $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$. Thus, the ${\mathrm{\ensuremath{\Lambda}}}_{\mathrm{s}}\mathrm{CDM}$ model provides remedy to various cosmological tensions simultaneously, only that the galaxy BAO data hinder its success to some extent.

Topics & Concepts