http://arxiv.org/abs/1402.0964
We use the clustering properties of Luminous Red Galaxies (LRGs) and of SDSS rich galaxy clusters in order to constrain the growth index ($\gamma$) of the linear matter fluctuations. We perform a standard $\chi^2$-minimization procedure between theoretical expectations and data, followed by a joint likelihood analysis and we find a value of $\gamma=0.54\pm 0.03$, perfectly consistent with the expectations of the $\Lambda$CDM model, and $\Omega_{m0} =0.30\pm 0.01$, in excellent agreement with the latest Planck results. Our analysis provides significantly more stringent growth index constraints with respect to previous studies, as indicated by the fact that the corresponding uncertainty is only $\sim 0.06 \gamma$. Finally, allowing $\gamma$ to vary with redshift we find degeneracies among the model parameters, as other similar studies. In order to alleviate the degeneracy we utilize a combined statistical analysis between our clustering and literature growth data and obtain more stringent constraints with respect to other recent studies.
Thu, 6 Feb 14
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