Cosmological large-scale structures beyond linear theory in modified gravity

Journal Article · Wed Jun 01 04:00:00 EDT 2011 · Journal of Cosmology and Astroparticle Physics

DOI:https://doi.org/10.1088/1475-7516/2011/06/019· OSTI ID:22277748

Bernardeau, Francis; Brax, Philippe ^[1]

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1. CEA, Institut de Physique Théorique, 91191 Gif-sur-Yvette Cédex (France)

We consider the effect of modified gravity on the growth of large-scale structures at second order in perturbation theory. We show that modified gravity models changing the linear growth rate of fluctuations are also bound to change, although mildly, the mode coupling amplitude in the density and reduced velocity fields. We present explicit formulae which describe this effect. We then focus on models of modified gravity involving a scalar field coupled to matter, in particular chameleons and dilatons, where it is shown that there exists a transition scale around which the existence of an extra scalar degree of freedom induces significant changes in the coupling properties of the cosmic fields. We obtain the amplitude of this effect for realistic dilaton models at the tree-order level for the bispectrum, finding them to be comparable in amplitude to those obtained in the DGP and f(R) models.

• OSTI ID: 22277748
• Journal Information: Journal of Cosmology and Astroparticle Physics, Journal Name: Journal of Cosmology and Astroparticle Physics Journal Issue: 06 Vol. 2011; ISSN 1475-7516
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
AMPLITUDES
ASTROPHYSICS
COMPARATIVE EVALUATIONS
COSMOLOGY
COUPLING
DEGREES OF FREEDOM
DENSITY
DILATONS
FLUCTUATIONS
GRAVITATION
PERTURBATION THEORY
SCALAR FIELDS
SCALARS
VELOCITY