2009/03/03 by Spyros Basilakos
Physics and Astronomy · #Age of the universe #Baryon acoustic oscillations #Cosmic microwave background #Cosmology #Cosmology and Gravitation Theories #Dark energy #Equation of state #Galaxies: Formation, Evolution, Phenomena #Hubble's law #Metric expansion of space #Particle physics theoretical and experimental studies #Scale factor (cosmology) #Structure formation #astro-ph.CO
paper · pdf · doi:10.1111/j.1365-2966.2009.14713.x
Accepted for publication, MNRAS, 10 pages, 5 figures
arxiv created 2009/03/03 · openalex publication_date 2009/04/24 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We study the dynamics of the Friedmann–Lemaitre–Robertson–Walker (FLRW) flat cosmological models in which the vacuum energy varies with time, Λ(t). In this model, we find that the main cosmological functions such as the scale factor of the universe and the Hubble flow are defined in terms of exponential functions. Applying a joint likelihood analysis of the recent Type Ia supernovae data, the cosmic microwave background shift parameter and the baryonic acoustic oscillations traced by the Sloan Digital Sky Survey (SDSS) galaxies, we place tight constraints on the main cosmological parameters of the Λ(t) scenario. Also, we compare the Λ(t) model with the traditional Λ cosmology and we find that the former model provides a Hubble expansion which compares well with that of the Λ cosmology. However, the Λ(t) scenario predicts stronger small scale dynamics, which implies a faster growth rate of perturbations with respect to the usual Λ cosmology, despite the fact that they share the same equation of state parameter. In this framework, we find that galaxy clusters in the Λ(t) model appear to form earlier than in the Λ model.