Gravity with perturbative constraints: Dark energy without new degrees of freedom

Alan Cooney, Simon Dedeo, Dimitrios Psaltis

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


Major observational efforts in the coming decade are designed to probe the equation of state of dark energy. Measuring a deviation of the equation-of-state parameter w from -1 would indicate a dark energy that cannot be represented solely by a cosmological constant. While it is commonly assumed that any implied modification to the ΛCDM model amounts to the addition of new dynamical fields, we propose here a framework for investigating whether or not such new fields are required when cosmological observations are combined with a set of minimal assumptions about the nature of gravitational physics. In our approach, we treat the additional degrees of freedom as perturbatively constrained and calculate a number of observable quantities, such as the Hubble expansion rate and the cosmic acceleration, for a homogeneous universe. We show that current observations place our universe within the perturbative validity of our framework and allow for the presence of nondynamical gravitational degrees of freedom at cosmological scales.

Original languageEnglish (US)
Article number044033
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Issue number4
StatePublished - Feb 26 2009

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Physics and Astronomy (miscellaneous)


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