Toward early dark energy and ns=1 with Planck, ACT, and SPT observations

We investigate the constraints on early dark energy (EDE) by combining the most recent CMB dataset favors nonzero EDE fractions and large Hubble constants. The inclusion of BAO + Pantheon data has little effect on the results, leads to H0 = 71.6(72.9)+2.0???1.5 and 73.17(72.74)+0.55 EDE and AdS-EDE, respectively. The axionlike EDE can fit the data significantly better (????2 ??? ???10) than ACDM, which is mainly driven by the ACT data. It is found again that if the current H0 measured locally is correct, complete resolution of the Hubble tension seems to be pointing toward a scale invariant HarrisonZeldovich spectrum of primordial scalar perturbation, i.e., ns = 1 for H0 ??? 73 km/s/Mpc.

Automated summary

This study investigates the constraints on early dark energy (EDE) by combining the latest CMB dataset. The results show the existence of nonzero EDE fractions and larger Hubble constants. The inclusion of BAO + Pantheon data has minimal impact on the findings. The data significantly favors axionlike EDE over the standard ACDM model.