2004/08/31 by Peng Wang, Xin-He Meng
Physics and Astronomy · #astro-ph
paper · pdf · doi:10.1088/0264-9381/22/2/003
published as Class.Quant.Grav. 22 (2005) 283-294 · 7 pages, 5 figures. v2: References added. v3: References added
arxiv created 2004/12/21 · arxiv updated 2009/12/01
We take a phenomenological approach to study the cosmological evolution of decaying vacuum cosmology (Λ(t)CDM) based on a simple assumption about the form of the modified matter expansion rate. In this framework, almost all the current vacuum decaying models can be unified in a simple manner. We argue that the idea of letting vacuum decay to resolve the fine-tuning problem is inconsistent with cosmological observations. We also discuss some issues in confronting Λ(t)CDM with observation. Using the effective equation of state formalism, we indicate that Λ(t)CDM is a possible candidate for phantom cosmology. Moreover, confronted with a possible trouble of effective equation of state formalism, we construct the effect dark energy density. Finally, we discuss the evolution of linear perturbation.