N on-linear evolution of f(R) cosm ologies II:power spectrum

By H. Oyaizu, Marcos Lima, Wayne Hu. 2008

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We carry out a suite of cosmological simulations of modified action f(R) models where cosmic acceleration arises from an alteration of gravity instead of dark energy. These models introduce an extra scalar degree of freedom which enhances the force of gravity below the inverse mass or Compton scale of the scalar. The simulations exhibit the so-called chameleon mechanism, necessary for satisfying local constraints on gravity, where this scale depends on environment, in particular, the depth of the local gravitational potential. We find that the chameleon mechanism can substantially suppress the enhancement of power spectrum in the nonlinear regime if the background field value is comparable to or smaller than the depth of the gravitational potentials of typical structures. Nonetheless power spectrum enhancements at intermediate scales remain at a measurable level for models even when the expansion history is indistinguishable from a cosmological constant, cold dark matter model. Simple scaling relations that take the linear power spectrum into a nonlinear spectrum fail to capture the modifications of f(R) due to the change in collapsed structures, the chameleon mechanism, and the time evolution of the modifications.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/800e9dbe8161385865b5afb98d8a9194a7110484

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Citations in the corpus

Approaches to understanding cosmic acceleration (2009, background): “Hence, while it is certain that |fR| must be small, any specific bound on its value today will be unreliable until galaxy formation in f (R) is studied in N-body numerical simulations—work that has only recently begun [167, 168].”
f(R) Theories (2010, methodology): “, cnl = 0) was derived by interpolating the N -body results in [479].”
Cosmology and Fundamental Physics with the Euclid Satellite (2012, methodology): “The first simulations of modified gravity cosmologies, limited to the “Chameleon” screening mechanism featured by f(R) theories, have been performed by means of mesh-based iterative relaxation schemes [921, 922, 1054, 665, 1279, 379, 1253] and showed an enhancement of the power spectrum amplitude at”