Accelerated inference on accelerated cosmic expansion: New constraints on axion-like early dark energy with DESI BAO and ACT DR6 CMB lensing

The early dark energy (EDE) extension to ΛCDM has been proposed as a candidate scenario to resolve the "Hubble tension". We present new constraints on the EDE model by incorporating new data from the Dark Energy Spectroscopic Instrument (DESI) Baryon Acoustic Oscillation (BAO) survey and CMB lensing measurements from the Atacama Cosmology Telescope (ACT) DR6 and Planck NPIPE data. We do not find evidence for EDE. The maximum fractional contribution of EDE to the total energy density is f_EDE< 0.091 (95% CL ) from our baseline combination of Planck CMB, CMB lensing, and DESI BAO. Our strongest constraints on EDE come from the combination of Planck CMB and CMB lensing alone, yielding f_EDE< 0.070 (95% CL ). We also explore extensions of ΛCDM beyond the EDE parameters by treating the total neutrino mass as a free parameter, finding ∑ m_ν < 0.096 eV (95% CL ) and f_EDE< 0.087 (95% CL ). For the first time in EDE analyses, we perform Bayesian parameter estimation using neural network emulators of cosmological observables, which are on the order of a hundred times faster than full Boltzmann solutions.