Saturday, 28 July 2007

Limits on the Dark Energy Parameters from Cosmic Microwave Background experiments

Dmitri Pogosyan1, J. Richard Bond2, Carlo Contaldi2

1Physics Department, University of Alberta, Edmonton, AB, T6G 2J1, Canada 2CITA, University of Toronto, Toronto, ON, M5S 3H8, Canada


Full suite of the present day Cosmic Microwave background (CMB) data, when combined with weak prior information on the Hubble constant and the age of the Universe, or the Large-Scale structure, provides strong indication for a non-zero density of the vacuum-like dark energy in our universe. This result independently supports the conclusions from Supernovae Ia (SN1a) data. When the model parameter space is extended to allow for the range of the equation of state parameter wQ for the dynamical field Q which gives rise to dark energy, the CMB data is found to give a weak upper bound wQ < −0.4 at 95% CL, however combined with SN1a data it strongly favours wQ < −0.8, consistent with -term like behaviour.