Freezing out early dark energy

Jannis Bielefeld, W. L. Kimmy Wu, Robert R. Caldwell, and Olivier Doré
Phys. Rev. D 88, 103004 – Published 7 November 2013

Abstract

A phenomenological model of dark energy that tracks the baryonic and cold dark matter at early times but resembles a cosmological constant at late times is explored. In the transition between these two regimes, the dark energy density drops rapidly as if it were a relic species that freezes out, during which time the equation of state peaks at +1. Such an adjustment in the dark energy density, as it shifts from scaling to potential domination, could be the signature of a trigger mechanism that helps explain the late-time cosmic acceleration. We show that the non-negligible dark energy density at early times, and the subsequent peak in the equation of state at the transition, leave an imprint on the cosmic microwave background anisotropy pattern and the rate of growth of large scale structure. The model introduces two new parameters, consisting of the present-day equation of state and the redshift of the freeze-out transition. A Monte Carlo Markov chain analysis of a ten-dimensional parameter space is performed to compare the model with pre-Planck cosmic microwave background, large scale structure and supernova data and measurements of the Hubble constant. We find that the transition described by this model could have taken place as late as a redshift z250. We explore the capability of future cosmic microwave background and weak lensing experiments to put tighter constraints on this model. The viability of this model may suggest new directions in dark-energy model building that address the coincidence problem.

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  • Received 23 May 2013

DOI:https://doi.org/10.1103/PhysRevD.88.103004

© 2013 American Physical Society

Authors & Affiliations

Jannis Bielefeld1, W. L. Kimmy Wu2, Robert R. Caldwell1, and Olivier Doré3,4

  • 1Department of Physics and Astronomy, Dartmouth College, 6127 Wilder Laboratory, Hanover, New Hampshire 03755, USA
  • 2Department of Physics, Stanford University, 382 Via Pueblo Mall, Stanford, California 94305-4060, USA and Kavli Institute for Particle Astrophysics and Cosmology, 452 Lomita Mall, Stanford, California 94305-4085, USA
  • 3NASA Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91125, USA
  • 4California Institute of Technology, MC249-17, Pasadena, California 91125, USA

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Issue

Vol. 88, Iss. 10 — 15 November 2013

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