We constrain the thermal evolution of the universe with a decaying cosmological term by using the method of the analysis for the Wilkinson Microwave Anisotropy Probe (WMAP) observation data. The cosmological term is assumed to be a function of the scale factor that increases toward the early universe, and the radiation energy density is lower compared to that in the model with the standard cosmological constant (ΛCDM). The decrease in the radiation density affects the thermal history of the universe; e.g. the photon decoupling occurs at higher-z compared to the case of the standard ΛCDM model. As a consequence, a decaying cosmological term affects the cosmic microwave background (CMB) anisotropy. Thanks to the Markov-Chain Monte Carlo method, we compare the angular power spectrum in the decaying ΛCDM model with the CMB data, and we get severe constraints on parameters of the model.
|Journal||Physical Review D - Particles, Fields, Gravitation and Cosmology|
|Publication status||Published - Jun 10 2008|
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics
- Physics and Astronomy (miscellaneous)