2021/03/31 by Saikat Chakraborty, Kelly MacDevette, Peter Dunsby +1
Physics and Astronomy · #Algorithm #Astrophysics #Black Holes and Theoretical Physics #Computer science #Cosmology #Cosmology and Gravitation Theories #Galaxies: Formation, Evolution, Phenomena #Instability #Lambda #Mathematical physics #Physics #Quantum mechanics #astro-ph.CO #gr-qc
paper · pdf · doi:10.1103/physrevd.103.124040
published as Phys. Rev. D 103, 124040 (2021) · 11 pages, 4 figures, figures improved, conclusion section modified
openalex created_date 2021/03/15 · arxiv created 2021/05/19 · openalex publication_date 2021/06/16 · arxiv updated 2021/06/22 · openalex updated_date 2026/08/05
We propose a new framework for studying the cosmology of f(R) gravity which completely avoids using the reconstruction program. This allows us to easily obtain a qualitative feel of how much the \mathrm\ensuremathΛCDM model differs from other f(R) theories of gravity at the level of linear perturbation theory for theories that share the same background dynamics. This is achieved by using the standard model independent cosmographic parameters to develop a new dynamical system formulation of f(R) gravity which is free from the limitation of having to first specify the functional form of f(R). By considering a set of representative trajectories, which are indistinguishable from \mathrm\ensuremathΛCDM, we use purely qualitative arguments to determine the extent to which these models deviate from the standard model by including an analysis of the linear growth rate of density fluctuations and also whether or not they suffer from the Dolgov-Kawasaki instability. We find that if one demands that a late time f(R) cosmology is observationally close to the \mathrm\ensuremathΛCDM model, there is a higher risk that it suffers from a Dolgov-Kawasaki instability. Conversely, the more one tries to construct a physically viable late time f(R) cosmology, the more likely it is observationally different from the \mathrm\ensuremathΛCDM model.