Resolving the Hubble tension with new early dark energy

By Florian Niedermann, M. Sloth. 2020

145 citations recorded by the source corpus.

New Early Dark Energy (NEDE) is a component of vacuum energy at the electron volt scale, which decays in a first order phase transition shortly before recombination [arXiv:1910.10739]. The NEDE component has the potential to resolve the tension between recent local measurements of the expansion rate of the universe using supernovae (SN) data, and the expansion rate inferred from the early universe through measurements of the Cosmic Microwave Background (CMB) when assuming $\Lambda$CDM. We discuss in depth the two-scalar field model of the NEDE phase transition including the process of bubble percolation, collision and coalescence. We also estimate the gravitational wave signal produced during the collision phase and argue that it can be searched for using pulsar timing arrays. In a second step, we construct an effective cosmological model, which describes the phase transition as an instantaneous process, and derive the covariant equations that match perturbations across the transition surface. Fitting the cosmological model to CMB, Baryonic Acoustic Oscillations and SN data, we report $H_0 = 69.6^{+1.0}_{-1.3} \, \textrm{km}\, \textrm{s}^{-1}\, \textrm{Mpc}^{-1}$ $(68 \%$ C.L.) without the local measurement of the Hubble parameter, bringing the tension down to $2.5\, \sigma$. Including the local input, we find $H_0 = 71.4 \pm 1.0 \, \textrm{km}\, \textrm{s}^{-1}\, \textrm{Mpc}^{-1}$ $(68 \%$ C.L.) and strong evidence for a non-vanishing NEDE component with a $\simeq 4\, \sigma$ significance.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/43215fbde5342b824ebb4ec7d9fdc43d51297363

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Citations in the corpus

The Ups and Downs of Early Dark Energy solutions to the Hubble tension: A review of models, hints and constraints circa 2023 (2023, background): “[83], the effective sound speed c 2 s in the NEDE fluid is set equal to the equation of state after the decay, i.”
Hubble Tension: The Evidence of New Physics (2023, background): “A similar first-order transition was implemented in early dark energy models [216], attempting to change the last scattering sound horizon scale without affecting other well-constrained cosmological observables.”