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

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 LCDM model is only less than a few percent even if the growth rate of first-order perturbations is significantly different from that in the LCDM 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.

15 pages, 1 figure, version to appear in JCAP

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Cited by in corpus (18)

• f(R) theories
• Solutions in the scalar-tensor theory with nonminimal derivative coupling
• Non-linear Evolution of Matter Power Spectrum in Modified Theory of Gravity
• The dispersion of growth of matter perturbations in f(R) gravity
• Constraining Modified Gravity and Growth with Weak Lensing
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• Signatures of Horndeski gravity on the Dark Matter Bispectrum
• Dark energy: investigation and modeling
• Hierarchical clustering in chameleon $f(R)$ gravity
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• Three-Point Correlations in f(R) Models of Gravity
• The Integrated Bispectrum in Modified Gravity Theories
• Complete density perturbations in the Jordan-Fierz-Brans-Dicke theory
• A new approach to cosmological perturbations in f(R) models
• Consistency Relations in Effective Field Theory
• De Sitter ground state of scalar-tensor gravity and its primordial perturbation
• Skewness of matter distribution in clustering dark energy cosmologies
• Probing gravity beyond general relativity with bispectrum multipoles of cosmological tracers: I. Theoretical Foundations