Does the fraction of dark matter diminish with early dark energy?
Hao Wang, Yun-Song Piao
Abstract
In prerecombination early dark energy (EDE) resolutions of the Hubble tension, the rise of Hubble constant value ${H}_{0}$ is usually accompanied with the exacerbation of so-called ${S}_{8}$ tension. Inspired by the swampland conjecture, we investigate what if a fraction ${f}_{*}$ of dark matter is coupled to EDE, ${m}_{\mathrm{cdm}}\ensuremath{\sim}\mathrm{exp}(\ensuremath{-}c\frac{|\mathrm{\ensuremath{\Delta}}{\ensuremath{\phi}}_{\mathrm{ede}}|}{{M}_{pl}})$ with $c\ensuremath{\sim}\mathcal{O}(1)$. We perform the Markov chain Monte Carlo analysis for the relevant EDE models with PlanckCMB, BAO, Pantheon and SH0ES dataset, as well as DES-Y1 data, and find that such a fraction helps to alleviate the ${S}_{8}$ tension. However, though $c\ensuremath{\gtrsim}0.1$ is allowed for a very small ${f}_{*}$, which suggests that a small fraction of dark matter has ever faded with EDE, $c\ensuremath{\sim}0$ is also consistent.