Improved Planck Constraints on Axionlike Early Dark Energy as a Resolution of the Hubble Tension
G. Efstathiou, Erik Rosenberg, Vivian Poulin
Abstract
Axionlike early dark energy (EDE) as an extension to $\mathrm{\ensuremath{\Lambda}}$ cold dark matter ($\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$) has been proposed as a possible solution to the ``Hubble tension.'' We revisit this model using a new cosmic microwave background (CMB) temperature and polarization likelihood constructed from the Planck NPIPE data release. In a Bayesian analysis, we find that the maximum fractional contribution of EDE to the total energy density is ${f}_{\mathrm{EDE}}<0.061$ (without SH0ES) over the redshift range $z\ensuremath{\in}[{10}^{3},{10}^{4}]$ and that the Hubble constant is constrained to lie within the range $66.9<{H}_{0}<69.5\text{ }\text{ }\mathrm{km}\text{ }{\mathrm{s}}^{\ensuremath{-}1}\text{ }{\mathrm{Mpc}}^{\ensuremath{-}1}$ (both at 95% C.L.). The data therefore favor a model close to $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$, leaving a residual tension of $3.7\ensuremath{\sigma}$ with the SH0ES Cepheid-based measurement of ${H}_{0}$. A comparison with the likelihood profile shows that our conclusions are robust to prior-volume effects. Our new CMB likelihood provides no evidence in favor of a significant EDE component.