Scale-dependence in $\Lambda$CDM parameters inferred from the CMB: a possible sign of Early Dark Energy

Understand

The early dark energy (EDE) model is one of the promising solutions to the Hubble tension.

• One of the successes of the EDE model is that it can provide a similar fit to the $\Lambda$CDM model for the CMB power spectrum.
• In this work, I analyze the phenomenology of the EDE and $\Lambda$CDM parameters on the CMB temperature power spectrum and notice that this cannot hold on all scales.
• Thus, if the real cosmology is as described by the EDE model, the $\Lambda$CDM parameters will be scale-dependent when fitting the CMB power spectrum with the $\Lambda$CDM model, which can be hints for the EDE model.