2005/11/22 by K. Koyama, Kazuya Koyama, Roy Maartens · 13 citations
Physics and Astronomy · #Astrophysics #Black Holes and Theoretical Physics #Brane #Brane cosmology #Classical mechanics #Cosmological constant #Cosmology #Cosmology and Gravitation Theories #Dark energy #Galaxies: Formation, Evolution, Phenomena #Galaxy #Gravitation #Inflation (cosmology) #Luminosity distance #Mathematical physics #Metric expansion of space #Physics #Redshift #Scale factor (cosmology) #Theoretical physics #Universe #Warp drive #astro-ph #gr-qc #hep-th
paper · pdf · doi:10.1088/1475-7516/2006/01/016
published as JCAP 0601:016,2006 · 6 pages, 2 figures
arxiv created 2005/11/22 · openalex publication_date 2006/01/18 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
The DGP brane-world model provides an alternative to the standard LCDM cosmology, in which the late universe accelerates due to a modification of gravity rather than vacuum energy. The cosmological constant Λ in LCDM is replaced by a single parameter, the crossover scale r c , in DGP. The supernova redshift observations can be fitted by both models, with Λ ∼ H 0 2 and r c ∼ H 0 −1 . This degeneracy is broken by structure formation, which is suppressed in different ways in the two models. There is some confusion in the literature about how the standard linear growth factor is modified in the DGP model. While the luminosity distance can be computed purely from the modified four-dimensional Friedman equation, the evolution of density perturbations requires an analysis of the five-dimensional gravitational field. We show that if the five-dimensional effects are inappropriately neglected, then the four-dimensional Bianchi identities are violated and the computed growth factor is incorrect. By using the five-dimensional equations, we derive the correct growth factor.