Dispersion of growth of matter perturbations inf(R)gravity

2009/08/19 by Shinji Tsujikawa, Radouane Gannouji, Bruno Moraes +1 · 1 citation
Physics and Astronomy · #Black Holes and Theoretical Physics #Cosmology and Gravitation Theories #Galaxies: Formation, Evolution, Phenomena #astro-ph.CO #gr-qc #hep-ph #hep-th

paper · pdf · doi:10.1103/physrevd.80.084044

published as Phys.Rev.D80:084044,2009 · 11 pages, 7 figures

arxiv created 2009/08/19 · openalex publication_date 2009/10/29 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28

Abstract

We study the growth of matter density perturbations \ensuremathδ_m for a number of viable f(R) gravity models that satisfy both cosmological and local gravity constraints, where the Lagrangian density f is a function of the Ricci scalar R. If the parameter m\ensuremath≡Rf_,RR/f_,R today is larger than the order of 10^\ensuremath-6, linear perturbations relevant to the matter power spectrum evolve with a growth rate s\ensuremath≡dln\ensuremathδ_m/dlna (a is the scale factor) that is larger than in the \ensuremathΛCDM model. We find the window in the free parameter space of our models for which spatial dispersion of the growth index \ensuremathγ₀\ensuremath≡\ensuremathγ(z=0) (z is the redshift) appears in the range of values 0.40\ensuremath\lesssim\ensuremathγ₀\ensuremath\lesssim0.55, as well as the region in parameter space for which there is essentially no dispersion and \ensuremathγ₀ converges to values around 0.40\ensuremath\lesssim\ensuremathγ₀\ensuremath\lesssim0.43. These latter values are much lower than in the \ensuremathΛCDM model. We show that these unusual dispersed or converged spectra are present in most of the viable f(R) models with m(z=0) larger than the order of 10^\ensuremath-6. These properties will be essential in the quest for f(R) modified gravity models using future high-precision observations and they confirm the possibility to distinguish clearly most of these models from the \ensuremathΛCDM model.

Citations

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• The Case for a Positive Cosmological Lambda-term
• Curvature Quintessence

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