http://arxiv.org/abs/1403.1259
Measurements of the linear growth factor $D$ at different redshifts $z$ are key to distinguish among cosmological models. One can estimate the derivative $dD(z)/d\ln(1+z)$ from redshift space measurements of the 3D anisotropic galaxy two-point correlation $\xi(z)$, but the degeneracy of its transverse (or projected) component with galaxy bias, i.e. $\xi_{\perp}(z) \propto\ D^2(z) b^2(z)$, introduces large errors in the growth measurement. In this paper we present a detailed comparison of two methods that have been proposed in the literature to break this degeneracy. Both propose measuring $b(z)$, and therefore $D(z)$ via $\xi_{\perp}$, by combining second- and third-order statistics. One uses the shape of the reduced three-point correlation and the other a combination of third-order one- and two-point cumulants. These methods take advantage of the fact that, for Gaussian initial conditions, the reduced third-order matter correlations are independent of redshift (and therefore of the growth factor) while the corresponding galaxy correlations depend on $b$. One can therefore measure $b$ and $D$ by comparing the second- and third-order matter correlations to those of galaxies. We use matter and halo catalogs from the MICE-GC simulation to test how well we can recover $b(z)$ and $D(z)$ with these methods in 3D real space. We also present a new approach, which enables us to measure $D$ directly from the redshift evolution of second- and third-order galaxy correlations without the need of modelling matter correlations. For haloes with masses lower than $10^{14}$ $h^{-1}$M$_\odot$, we find a $10$ percent agreement between the different estimates of $D$. At higher masses we find larger differences that can probably be attributed to the breakdown of the local quadratic bias model and non-Poissonian shot-noise.
K. Hoffmann, J. Bel, E. Gaztanaga, et. al.
Fri, 7 Mar 14
46/47