Observational constrains on the cosmology with a decaying cosmological term

12/2006; -1:149.
Source: arXiv

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 cos- mological "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 back- ground anisotropy. We show the angular power
spectrum in DΛCDM model and compare with the Wilkinson Microwave
Anisotropy Probe (WMAP) data.

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