Parallel Talk | Cosmology from Home 2020
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Talk title:
Early Dark Energy and Cosmological Concordance

Talk abstract:
The early dark energy (EDE) scenario has been posited as a resolution to the persistent tension between early- and late-universe inferences of the Hubble constant. This scenario invokes a new component in the early universe that acts to decrease the physical size of the sound horizon imprinted in the cosmic microwave background (CMB) and thereby increase the inferred H_0 value. However, the CMB-preferred value of the density fluctuation amplitude, sigma_8, increases in EDE as compared to LCDM, increasing tension with large-scale structure (LSS) data. In this talk, I will demonstrate that the EDE model fit to CMB and SH0ES data yields scale-dependent changes in the matter power spectrum compared to LCDM, including 10% more power at k = 1 h/Mpc. Motivated by this observation, I will present a re-analysis of the EDE scenario, considering LSS data in detail, as well as the first search for EDE in Planck data alone, which yields no evidence for EDE. I will show that the inclusion of LSS data from DES, KiDS, and HSC weakens evidence for the existence of EDE, and that further inclusion of a BOSS likelihood employing the effective field theory of LSS additionally tightens the bound. A joint analysis of cosmological data sets without SH0ES shows no evidence for EDE, and yields an H_0 value that is in significant tension with SH0ES. Thus, the EDE scenario as currently formulated is unlikely to restore cosmological concordance.

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