The Atacama Cosmology Telescope: Constraints on Pre-Recombination Early Dark Energy

J. Colin Hill , Erminia Calabrese , Simone Aiola , Nicholas Battaglia , Boris Bolliet , Steve K. Choi , Mark J. Devlin , Adriaan J. Duivenvoorden , Jo Dunkley , Simone Ferraro , Patricio A. Gallardo , Vera Gluscevic , Matthew Hasselfield , Matt Hilton , Adam D. Hincks , Renee Hlozek , Brian J. Koopman , Arthur Kosowsky , Adrien La Posta (1) , Thibaut Louis (1) , Mathew S. Madhavacheril , Jeff Mcmahon , Kavilan Moodley , Sigurd Naess , Umberto Natale , Federico Nati , Laura Newburgh , Michael D. Niemack , Lyman A. Page , Bruce Partridge , Frank J. Qu , Maria Salatino , Alessandro Schillaci , Neelima Sehgal , Blake D. Sherwin , Cristobal Sifon , David N. Spergel , Suzanne T. Staggs , Emilie R. Storer , Alexander van Engelen , Eve M. Vavagiakis , Edward J. Wollack , Zhilei Xu

1 IJCLab - Laboratoire de Physique des 2 Infinis Irène Joliot-Curie

The early dark energy (EDE) scenario aims to increase the value of the Hubble constant ($H_0$) inferred from cosmic microwave background (CMB) data over that found in $\Lambda$CDM, via the introduction of a new form of energy density in the early universe. The EDE component briefly accelerates cosmic expansion just prior to recombination, which reduces the physical size of the sound horizon imprinted in the CMB. Previous work has found that non-zero EDE is not preferred by Planck CMB power spectrum data alone, which yield a 95% confidence level (CL) upper limit $f_{\rm EDE} < 0.087$ on the maximal fractional contribution of the EDE field to the cosmic energy budget. In this paper, we fit the EDE model to CMB data from the Atacama Cosmology Telescope (ACT) Data Release 4. We find that a combination of ACT, large-scale Planck TT (similar to WMAP), Planck CMB lensing, and BAO data prefers the existence of EDE at $>99.7$% CL: $f_{\rm EDE} = 0.091^{+0.020}_{-0.036}$, with $H_0 = 70.9^{+1.0}_{-2.0}$ km/s/Mpc (both 68% CL). From a model-selection standpoint, we find that EDE is favored over $\Lambda$CDM by these data at roughly $3\sigma$ significance. In contrast, a joint analysis of the full Planck and ACT data yields no evidence for EDE, as previously found for Planck alone. We show that the preference for EDE in ACT alone is driven by its TE and EE power spectrum data. The tight constraint on EDE from Planck alone is driven by its high-$\ell$ TT power spectrum data. Understanding whether these differing constraints are physical in nature, due to systematics, or simply a rare statistical fluctuation is of high priority. The best-fit EDE models to ACT and Planck exhibit coherent differences across a wide range of multipoles in TE and EE, indicating that a powerful test of this scenario is anticipated with near-future data from ACT and other ground-based experiments.

Mots clés: cosmic background radiation: power spectrum; fluctuation: statistical; energy: density; satellite: Planck; cosmological model: parameter space; dark energy; multipole; recombination; coherence; Hubble constant; gravitation: lens; horizon: acoustic; fractional; WMAP; expansion: acceleration; statistical analysis: confidence limit; baryon: oscillation: acoustic

Domaines: Astrophysique [astro-ph]; Relativité Générale et Cosmologie Quantique [gr-qc]; Physique des Hautes Energies - Phénoménologie [hep-ph]

J. Colin Hill, Erminia Calabrese, Simone Aiola, Nicholas Battaglia, Boris Bolliet, et al.. The Atacama Cosmology Telescope: Constraints on Pre-Recombination Early Dark Energy. Physical Review D, 2022, 105 (12), pp.123536. ⟨10.1103/PhysRevD.105.123536⟩. ⟨hal-03356427⟩