Abstract
To describe dark energy we introduce a fluid model with no free parameter on the microscopic level. The constituents of this fluid are massless particles which are a dynamical realization of the unextended Galilei algebra. These particles are exotic as they live in an enlarged phase space. Their only interaction is with gravity. A minimal coupling to the gravitational field, satisfying Einstein’s equivalence principle, leads to a dynamically active gravitational mass density of either sign. A two-component model containing matter (baryonic and dark) and dark energy leads, through the cosmological principle, to Friedmann-like equations. Their solutions show a deceleration phase for the early universe and an acceleration phase for the late universe. We predict the Hubble parameter and the deceleration parameter and compare them with available experimental data. We also discuss a reduced model (one-component dark sector) and the inclusion of radiation. Our model shows no stationary modification of Newton’s gravitational potential.
- Received 28 April 2009
DOI:https://doi.org/10.1103/PhysRevD.80.083513
©2009 American Physical Society