Primordial Bounce-Inflation Scenario to Alleviate Cosmological Tensions and Lensing Anomaly

Hao-Hao Li; Xin-zhe Zhang; Taotao Qiu

doi:10.1016/j.scib.2025.01.007

paper

Primordial Bounce-Inflation Scenario to Alleviate Cosmological Tensions and Lensing Anomaly

arXiv:2409.04027 · doi:10.1016/j.scib.2025.01.007

Abstract

We put forward a primordial scenario to alleviate cosmological tensions, i.e. Hubble ( $H_{0}$ ) tension and $S_{8}$ tension. Based on flat $Λ$ CDM, the Bounce-Inflation (BI) scenario gives the results that $H_{0} = 68.6 0_{- 0.45}^{+ 0.40} km / s / Mpc$ , $S_{8} = 0.806 \pm 0.011$ by using \texttt{Planck 2018} data sets and $H_{0} = 68.96 \pm 0.38 km / s / Mpc$ , $S_{8} = 0.797 \pm 0.010$ by using \texttt{Planck 2018} + \texttt{SPT3G} data sets. These reduce the cosmological tensions slightly. We also take an extended $Λ$ CDM model into account, $Λ$ CDM (BI)+ $A_{L}$ , where $A_{L}$ is the gravitational lensing amplitude. The results are $H_{0} = 69.38 \pm 0.49 km / s / Mpc$ , $S_{8} = 0.774 \pm 0.014$ fitted by \texttt{Planck 2018} data sets and $H_{0} = 69.49 \pm 0.45 km / s / Mpc$ , $S_{8} = 0.77 1_{- 0.012}^{+ 0.013}$ fitted by \texttt{Planck 2018} + \texttt{SPT3G} data sets, which reduce the Hubble tension to $\sim 3 σ$ level and show no $S_{8}$ tension. The $A_{L} \approx 1.1$ is smaller than the result of the inflation scenario with a constraint of \texttt{Planck 2018} data sets. Besides, the spectral index of the bounce-inflation scenario $n_{s}$ is about $0.98$ , with a trend to the Harrison-Zel'dovich spectrum.

3 pages, 2 figures, 1 table, science bulletin accepted

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