Improved Planck Constraints on Axionlike Early Dark Energy as a Resolution of the Hubble Tension.

Abstract

Axionlike early dark energy (EDE) as an extension to Λ cold dark matter (ΛCDM) 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_{EDE}<0.061 (without SH0ES) over the redshift range z∈[10^{3},10^{4}] and that the Hubble constant is constrained to lie within the range 66.9<H_{0}<69.5 km s^{-1} Mpc^{-1} (both at 95%C.L.). The data therefore favor a model close to ΛCDM, leaving a residual tension of 3.7σ 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.