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 $\hat{I}{›}_{\mathrm{s}}$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 $z_{†}\sim 2$, inspired by the graduated dark energy model proposed in Akarsu et al. [Phys. Rev. D 101, 063528 (2020)]. $\hat{I}{›}_{\mathrm{s}}$CDM was previously claimed to simultaneously relax five cosmological discrepancies, namely, the $H_0$, $S_8$, and $M_B$ tensions along with the Ly-$\hat{I}\pm$ and $\ddot{I}{‰}_{\mathrm{b}}$ anomalies, which prevail within the standard $\hat{I}›$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 $\hat{I}{›}_{\mathrm{s}}$CDM exhibits a better fit to the data compared to $\hat{I}›$CDM, and simultaneously relaxes the six discrepancies of $\hat{I}›$CDM, viz., the $H_0$, $M_B$, $S_8$, Ly-$\hat{I}\pm$, $t_0$, and $\ddot{I}{‰}_{\mathrm{b}}$ discrepancies, all of which are discussed in detail. When the $M_B$ prior is included in the analyses, $\hat{I}{›}_{\mathrm{s}}$CDM performs significantly better in relaxing the $H_0$, $M_B$, and $S_8$ tensions with the constraint $z_{†}\sim 1.8$ even when the Ly-$\hat{I}\pm$ data (which imposed the $z_{†}\sim 2$ constraint in the previous studies) are excluded. In contrast, the presence of the $M_B$ prior causes only negligible improvements for $\hat{I}›$CDM. Thus, the $\hat{I}{›}_{\mathrm{s}}$CDM model provides remedy to various cosmological tensions simultaneously, only that the galaxy BAO data hinder its success to some extent.

27 pages, 11 figures, 5 tables; matches the version published in Physical Review D