Next Generation Redshift Surveys and the Origin of Cosmic Acceleration

Viviana Acquaviva; Amir Hajian; David N. Spergel; Sudeep Das

doi:10.1103/PhysRevD.78.043514

paper

Next Generation Redshift Surveys and the Origin of Cosmic Acceleration

arXiv:0803.2236 · doi:10.1103/PhysRevD.78.043514

Abstract

Cosmologists are exploring two possible sets of explanations for the remarkable observation of cosmic acceleration: dark energy fills space or general relativity fails on cosmological scales. We define a null test parameter $ε (k, a) \equiv Ω_{m}^{- γ} d ln D / d ln a - 1$ , where $a$ is the scale factor, $D$ is the growth rate of structure, $Ω_{m} (a)$ is the matter density parameter, and $γ$ is a simple function of redshift. We show that it can be expressed entirely in terms of the bias factor, $b (a)$ , (measured from cross-correlations with CMB lensing) and the amplitude of redshift space distortions, $β (k, a)$ . Measurements of the CMB power spectrum determine $Ω_{m 0} H_{0}^{2}$ . If dark energy within GR is the solution to the cosmic acceleration problem, then the logarithmic growth rate of structure $d ln D / d ln a = Ω_{m}^{γ}$ . Thus, $ε (k, a) = 0$ on linear scales to better than 1%. We show that in the class of Modified Gravity models known as $f (R)$ , the growth rate has a different dependence on scale and redshift. By combining measurements of the amplitude of $β$ and of the bias, $b$ , redshift surveys will be able to determine the logarithmic growth rate as a function of scale and redshift. We estimate the predicted sensitivity of the proposed SDSS III (BOSS) survey and the proposed ADEPT mission and find that they will test structure growth in General Relativity to the percent level.

Revised version accepted for publication in Physical Review D

Next Generation Redshift Surveys and the Origin of Cosmic Acceleration

Abstract

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