Early Dark Energy Does Not Restore Cosmological Concordance
Link to paper: [2003.07355] Early Dark Energy Does Not Restore Cosmological Concordance, by J. Colin Hill, Evan McDonough, Michael W. Toomey, Stephon Alexander
Updates since this was originally posted:
- [2109.04451] The Atacama Cosmology Telescope: Constraints on Pre-Recombination Early Dark Energy , J. Colin Hill, et. al. Colin presents these results in a colloquium talk on 09-Sep-2021.
- In [2009.10740] Early dark energy is not excluded by current large-scale structure data a rebuttal is made and the authors “suggest that EDE still provides a potential resolution to the Hubble tension and that it is worthwhile to test the predictions of EDE with future data-sets and further study its theoretical possibilities.”
- Lead author Colin Hill was interviewed in a Cosmology Talk episode by Shaun Hotchkiss: Early dark energy doesn't make cosmology concordant again. Links to key parts of the video are available at the talk page.
- A detailed review of this paper was posted by cosmologist Sunny Vagnozzi on his blog here
- Follow-up paper: [2006.11235] Constraining Early Dark Energy with Large-Scale Structure, by Mikhail M. Ivanov, Evan McDonough, J. Colin Hill, Marko Simonović, Michael W. Toomey, Stephon Alexander, Matias Zaldarriaga. An astrobites article about it.
Background
Going back at least several years [1], but increasingly since late-2018 [2-7], there has been growing theoretical interest for the Hubble tension issue that suggests new physics models may be needed for the early universe prior to recombination that do not cause changes to late time cosmology, since that is tightly-constrained [4, 8].
For example, papers [2, 5] propose models for a new form of early dark energy (EDE) present at z ≳ 3000 that then dilutes away, resulting in a reduced sound horizon at decoupling. This results in a larger inferred $H_0$ value from CMB data versus Planck results, thus reducing the disparity between early and late time $H_0$ results.
These EDE proposals for resolving $H_0$ tension were characterized as being somewhere on the spectrum between “most plausible” [3] to “least unlikely” [4].