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

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 fEDE<0.061 (without SH0ES) over the redshift range z∈[10³,10⁴] and that the Hubble constant is constrained to lie within the range 66.9<H₀<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 H₀. 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.