A grounded perspective on New Early Dark Energy using ACT, SPT, and BICEP/Keck

Juan S. Cruz, Florian Niedermann, Martin S. Sloth

Submitted on 6 September 2022


We examine further the ability of the New Early Dark Energy model (NEDE) to resolve the current tension between the Cosmic Microwave Background (CMB) and local measurements of H0 and the consequences for inflation. We perform new Bayesian analyses, including the current datasets from the ground-based CMB telescopes Atacama Cosmology Telescope (ACT), the South Pole Telescope (SPT), and the BICEP/Keck telescopes, employing an updated likelihood for the local measurements coming from the SH0ES collaboration. Using the SH0ES prior on H0, the combined analysis with Baryonic Acoustic Oscillations (BAO), Pantheon, Planck and ACT improves the best-fit by Δχ2=15.9 with respect to ΛCDM, favors a non-zero fractional contribution of NEDE, fNEDE>0, by 4.8σ, and gives a best-fit value for the Hubble constant of H0=72.09 km/s/Mpc (mean 71.480.81+0.79 with 68% C.L.). A similar analysis using SPT instead of ACT yields consistent results with a Δχ2=23.1 over ΛCDM, a preference for non-zero fNEDE of 4.7σ and a best-fit value of H0=71.77 km/s/Mpc (mean 71.430.84+0.84 with 68% C.L.). We also provide the constraints on the inflation parameters r and ns coming from NEDE, including the BICEP/Keck 2018 data, and show that the allowed upper value on the tensor-scalar ratio is consistent with the ΛCDM bound, but, as also originally found, with a more blue scalar spectrum implying that the simplest curvaton model is now favored over the Starobinsky inflation model.


Comment: 32 pages, 10 figures, 14 tables

Subjects: Astrophysics - Cosmology and Nongalactic Astrophysics; High Energy Physics - Phenomenology; High Energy Physics - Theory