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].

Findings from this New Paper

This new paper by Colin Hill et al analyzed these EDE models in relation to a number of data set combinations, including large scale structure data. In particular, the EDE proposals run into problems with LSS data. If interested, you can read the details but here's some of their summary conclusions:

“We conclude that the EDE scenario is, at best, no more likely to be concordant with all current cosmological data sets than ΛCDM, and appears unlikely to resolve the $H_0$ tension.” (pg1)

“There is no sign of concordance amongst these data sets: the LSS data pull the parameters in the opposite direction to that required to simultaneously fit the CMB and SH0ES data.” (pg 26)

“Taken in conjunction, these results paint a bleak picture for the viability of the EDE scenario as a candidateto restore cosmological concordance. More generally, it is likely that any model that attempts to decrease the sound horizon by increasing H(z) through a new dark-energy-like component that is active at early times will encounter the problems identified here. All such models, insofar as they can accommodate a close fit to both the CMB and SH0ES measurement, will do so at the cost of a shift in ΛCDM parameters that is not compatible with LSS data.” (pg 27)

“In the absence of significant shifts with respect to current LSS data, it seems unlikely that these next-generation data sets (WFIRST, DESI, VRO, etc) will reverse the negative trajectory we have seen here in the evidence for EDE as LSS data are included in the analysis.” (pg 27) -—

[1] [1607.05617] The trouble with $H_0$ [2] [1811.04083] Early Dark Energy Can Resolve The Hubble Tension [3] [1907.10625] Tensions between the Early and the Late Universe [4] [1908.03663] The Hubble Hunter's Guide [5] [1908.06995] Oscillating scalar fields and the Hubble tension: a resolution with novel signatures [6] [1911.11760] Early dark energy from massive neutrinos — a natural resolution of the Hubble tension. Some reactions to this paper in this thread . [7] The subject paper lists additional EDE proposals, see page 26 for additional references. [8] “there is not much freedom in changing the expansion history from that of a standard ΛCDM model below z ∼ 2: the guardrails offered by SNe and BAO do not allow this.” [1, pg 7]

Tags: #Cosmology #DE #H0