Papers › A grounded perspective on New Early Dark Energy using ACT, SPT, and BICEP/Keck
A grounded perspective on New Early Dark Energy using ACT, SPT, and BICEP/Keck
Juan S. Cruz, Florian Niedermann, Martin S. Sloth
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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 S$H_0$ES collaboration. Using the S$H_0$ES 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, f_(NEDE) > 0, by 4.8σ, and gives a best-fit value for the Hubble constant of H₀ = 72.09 km/s/Mpc (mean 71.48_(-0.81)^(+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 f_(NEDE) of 4.7σ and a best-fit value of H₀=71.77 km/s/Mpc (mean 71.43_(-0.84)^(+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.
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