Observational constraints on a decaying cosmological term

Abstract

We investigate the evolution of a universe with a decaying cosmological term (vacuum energy) that is assumed to be a function of the scale factor. In this model, while the cosmological term increases to the early universe, the radiation energy density is lower than the model with the cosmological "constant". We find that the effects of the decaying cosmological term on the expansion rate at the redshift z<2 is negligible. However, the decrease in the radiation density affects on 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 on the cosmic microwave background anisotropy. We show the angular power spectrum in DΛCDM model and compare with the Wilkinson Microwave Anisotropy Probe (WMAP) data.

5 pages, 3 figures, Proceedings of International Symposium on Nuclear Astrophysics -Nuclei in the Cosmos IX-, CERN, Geneva, June 25-30, 2006

References in corpus (7)

• Wilkinson Microwave Anisotropy Probe (WMAP) Three Year Results: Implications for Cosmology
• Cosmological Results from High-z Supernovae
• Three-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Temperature Analysis
• First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Parameter Estimation Methodology
• Evolution of the Scale Factor with a Variable Cosmological Term
• Constraints on the coupled quintessence from cosmic microwave background anisotropy and matter power spectrum
• Big-bang nucleosynthesis in Brans-Dicke cosmology with a varying $\Lambda$ term related to WMAP