Exploring $Λ$CDM extensions with SPT-3G and Planck data: 4$σ$ evidence for neutrino masses and implications of extended dark energy models for cosmological tensions

Abstract: We present new cosmological constraints in a set of motivated extensions of the $\Lambda$CDM model using the polarization and gravitational lensing measurements from the South Pole Telescope and the Planck CMB temperature observations at large angular scales. In all cosmological scenarios, this CMB data brings the clustering measurements into agreement with the low-redshift probes of large-scale structure. Combining the SPT-3G, SPTpol and Planck large-scale temperature data with the latest full-shape BOSS and BAO measurements, information from the weak lensing and photometric galaxy clustering, and Pantheon supernova set we find a $4\sigma$ evidence for nonzero neutrino mass, $\sum m_\nu=0.22\pm0.06\,{\rm eV}$.Breaking the CMB degeneracies between $\sum m_\nu$ and the cosmological parameters by the BOSS data is a major contribution to our neutrino mass measurement. The future CMB data would allow for investigating this measurement. Then we explore the possibility of dynamical dark energy with two model-independent approaches: one introduces a phantom crossing in dark energy equation of state, another provides with a sharp transition in the dark energy evolution. For the combination of all data considered, the both models predict $H_0\simeq68\,{\rm km\,s^{-1}Mpc^{-1}}$ being in a $\sim3\sigma$ tension with the SH0ES constraint. However, when the local Type Ia supernovae are calibrated by Cepheids, the late Universe scenarios suggest significantly higher values of $H_0$ consistent with SH0ES. Our work draws attention to the supernova absolute magnitude calibration as one of the issues on the way to reconcile the $H_0$ tension.