Atacama Cosmology Telescope: Constraints on prerecombination early dark energy

Hill, J. Colin; Calabrese, Erminia; Aiola, Simone; Battaglia, Nicholas; Bolliet, Boris; Choi, Steve K.; Devlin, Mark J.; Duivenvoorden, Adriaan J.; Dunkley, Jo; Ferraro, Simone

doi:10.1103/PhysRevD.105.123536

Atacama Cosmology Telescope: Constraints on prerecombination early dark energy

J. Colin Hill
(
- Columbia U. and
- CCA, New York
)
,
Erminia Calabrese
(
- Cardiff U.
)
,
Simone Aiola
(
- CCA, New York
)
,
Nicholas Battaglia
(
- Cornell U.
)
,
Boris Bolliet
(
- Columbia U.
)

Sep 9, 2021

45 pages

Published in:

Phys.Rev.D 105 (2022) 12, 123536

Published: Jun 15, 2022

e-Print:

2109.04451 [astro-ph.CO]

DOI:

10.1103/PhysRevD.105.123536 (publication)

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Abstract: (APS)

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 the standard cosmological model (

Λ 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 nonzero EDE is not preferred by Planck CMB power spectrum data alone, which yield a 95% confidence level (C.L.) upper limit

f_{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 % C . L .

:

f_{EDE} = 0.09 1_{- 0.036}^{+ 0.020}

, with

H_{0} = {70.9}_{- 2.0}^{+ 1.0} km / s / Mpc

(both 68% C.L.). From a model-selection standpoint, we find that EDE is favored over

Λ CDM

by these data at roughly

3 σ

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-

ℓ 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.

Note:

v1: 25+20 pages, 6+18 figures, submitted to PRD; v2: 26+20 pages, 7+18 figures, results unchanged, matches PRD accepted version. MCMC chains available at https://lambda.gsfc.nasa.gov/product/act/actpol_mcmc_chains_get.html

cosmic background radiation: power spectrum
fluctuation: statistical
energy: density
satellite: Planck
cosmological model: parameter space
dark energy
multipole
recombination
coherence
Hubble constant