Observational constraints on a decaying cosmological term

Riou Nakamura, Masa Aki Hashimoto, Kiyotomo Ichiki

Research output: Contribution to journalConference articlepeer-review


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 DLCDM model and compare with the Wilkinson Microwave Anisotropy Probe (WMAP) data.

Original languageEnglish
JournalProceedings of Science
Publication statusPublished - 2006
Event9th International Symposium on Nuclear Astrophysics - Nuclei in the Cosmos, NIC 2006 - Geneva, Switzerland
Duration: Jun 25 2006Jun 30 2006

All Science Journal Classification (ASJC) codes

  • General


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