Robust constraints on dark energy and gravity from galaxy clustering data

July 2012 • 2012MNRAS.423.3631W

Authors • Wang, Yun

Abstract • Galaxy clustering data provide a powerful probe of dark energy. We examine how the constraints on the scaled expansion history of the Universe, x_h(z) =H(z)s (with s denoting the sound horizon at the drag epoch), and the scaled angular diameter distance, x_d(z) =D_A(z)/s, depend on the methods used to analyse the galaxy clustering data. We find that using the observed galaxy power spectrum, P^obs_g(k), x_h(z) and x_d(z) are measured more accurately and are significantly less correlated with each other, compared to using only the information from the baryon acoustic oscillations (BAO) in P^obs_g(k). Using the {x_h(z), x_d(z)} from P^obs_g(k) gives a Dark Energy Task Force (DETF) dark energy figure of merit (FoM) approximately a factor of 2 larger than using the {x_h(z), x_d(z)} from BAO only; this provides a robust conservative method to go beyond BAO only in extracting dark energy information from galaxy clustering data.

We find that a Stage IV galaxy redshift survey, with 0.7 < z < 2 over 15 000 (deg)², can measure ? with high precision [where f_g(z) and G(z) are the linear growth rate and factor of large-scale structure, respectively, and ? is the dimensionless normalization of P^obs_g(k)], when redshift-space distortion information is included. The measurement of ? provides a powerful test of gravity, and significantly boosts the dark energy FoM when general relativity is assumed.

Links

• PDF https://academic.oup.com/mnras/pdf-lookup/doi/10.1111/j.1365-2966.2012.21170.x
• PREPRINT http://arxiv.org/abs/1202.5238
• ELECTR http://dx.doi.org/10.1111/j.1365-2966.2012.21170.x