Phenomenological gravitational phase transition: Early and late modifications
Nima Khosravi, M. Farhang
Abstract
In this work we generalize the idea of a gravitational phase transition, or GPT, at late times [M. Farhang and N. Khosravi, Phys. Rev. D 103, 083523 (2021)] to allow for a modified gravity scenario in the early Universe as well. The original GPT was shown to simultaneously relax the ${H}_{0}$ and ${\ensuremath{\sigma}}_{8}$ tensions and Planck internal inconsistencies. However, the primary results from GPT predictions implied disagreement with the data from the baryonic acoustic oscillations (BAO). Here we investigate whether the generalized GPT scenario could address the Hubble tension in the presence of the BAO data as well. We find that, despite the vastly enlarged gravitational parameter space, the BAO data strongly prefer the $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$ paradigm with a low inferred Hubble constant, $68.03\ifmmode\pm\else\textpm\fi{}0.76\text{ }\text{ }\mathrm{km}/\mathrm{s}/\mathrm{Mpc}$, in tension with the local ${H}_{0}$ measurements from Riess et al. [Astrophys. J. 876, 85 (2019)], ${H}_{0}=74.03\ifmmode\pm\else\textpm\fi{}1.42\text{ }\text{ }\mathrm{km}/\mathrm{s}/\mathrm{Mpc}$. This failure of the generalized GPT scenario to host both various early and late datasets is of significance and noticeably shrinks the space of possible gravitational solutions to the Hubble tension.