Constraining deviations from Newton's law of gravity on cosmological scales: confrontation to power spectrum of SDSS galaxies

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  • 21 January 2005
Abstract
In spite of the growing observational evidence for dark matter and dark energy in the universe, their physical nature is still largely unknown. In fact several authors have recently proposed modifications of Newton's law of gravity on cosmological scales as an alternative idea to account for the currently accelerating universe. Inspired by such recent proposals, we attempt to constrain possible deviations from Newton's law of gravity by means of the clustering of SDSS (Sloan Digital Sky Survey) galaxies. To be specific, we assume a simple gravity law model with an additional Yukawa-type term characterized by the amplitude \alpha and the length scale \lambda. Adopting spatially-flat universes dominated by cold dark matter and/or dark energy, we solve a linear perturbation equation for density fluctuations. In particular, we find an exact analytic solution in the Einstein -- de Sitter universe. Following the Peacock-Dodds prescription, we compute the nonlinear power spectra of mass fluctuations, perform the statistical comparison with the SDSS galaxy data, and derive the constraints on the \alpha-\lambda plane; for instance, we obtain the constraints (99.7% confidence level) of -0.5<\alpha <0.6 and -0.8<\alpha<0.9 for \lambda=5h^{-1}Mpc and 10h^{-1}Mpc, respectively. We also discuss several future directions to improve our analysis in constraining non-Newtonian gravity models.

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