Work

Second-order matter density perturbations and skewness in scalar–tensor modified gravity models

Year: 2008

Type: article

Abstract: We study second-order cosmological perturbations in scalar–tensor models of dark energy that satisfy local gravity constraints, including f ( R ) gravity. We derive equations for matter fluctuations under a sub-horizon approximation and clarify conditions under which first-order perturbations in the scalar field can be neglected relative to second-order matter and velocity perturbations. We also compute the skewness of the matter density distribution and find that the difference from the ΛCDM (CDM: cold dark matter) model is less than a few per cent even if the growth rate of first-order perturbations is significantly different from that in the ΛCDM model. This shows that the skewness provides a model-independent test for the picture of gravitational instability from Gaussian initial perturbations including scalar–tensor modified gravity models.

Source: Journal of Cosmology and Astroparticle Physics

DOI: 10.1088/1475-7516/2008/09/009

Authors: Takayuki Tatekawa, Shinji Tsujikawa

Institutions: Kogakuin University, Waseda University, Ochanomizu University, Waseda Research Institute for Science and Engineering, Tokyo University of Science

Language: English

Topic: Cosmology and Gravitation Theories

Subfield: Astronomy and Astrophysics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: green

Funder: Japan Society for the Promotion of Science

Award: G2422244586