Looking for an extra dimension with tomographic cosmic shear.pdf

a r X i v : a s t r o - p h / 0 4 0 7 4 8 9 v 4 3 0 O c t 2 0 0 5 Looking for an extra dimension with tomographic cosmic shear Yong-Seon Song? Enrico Fermi Institute, University of Chicago, Chicago IL 60637 (Dated: February 2, 2008) The cosmic acceleration was discovered in one of the brane-based models. We are interested in discriminating this model from the dark energy by tomographic cosmic shear. Growth factors are different in the two models when one adjusts parameters to get nearly identical H(z). The two models could be distinguished with independent determinations of both geometrical factors and the growth factor. We introduce new parameterizations to separate the influence of geometry and the influence of growth on cosmic shear maps. We find that future observations will be able to distinguish between both models. PACS numbers: draft I. INTRODUCTION The discovery of cosmic acceleration [1, 2, 3] has led to theoretical efforts to understand the nature of the cos- mic acceleration [4, 5, 6, 7] and phenomenological efforts to discriminate the diverse modelings [8, 9, 10, 11, 12, 13, 14]. Most theoretical explanations for the acceler- ation preserve Einstein gravity and add a new smooth and dark component called Dark Energy (DE) [4, 5]. However, DE is not yet strongly supported theoretically nor phenomenologically. The similar cosmic acceleration was also discovered in one of brane-based models [6] by C. Deffayet et.al. [15, 16] (hereafter DGP model rep- resents this discovery of the cosmic acceleration in the brane-based model [6].) In the DGP model, the cosmic acceleration is gener- ated by the modified gravity due to the presence of the extra dimension in DGP. The study of the extra dimen- sion physics influencing the DGP model has been inves- tigated by [17, 18, 19]. Dvali, Gabadadze and Porrati designed a brane where ordinary matter is embedded in an infinite extra dimension and gravity is modified at larger scale [6]. The model (DGP) which generates t