Precision growth index using the clustering of cosmic structures and growth data

Abstract

Abstract:We use the clustering properties of Luminous Red Galaxies (LRGs) and the growth rate data provided by the various galaxy surveys in order to constrain the growth index (γ) of the linear matter fluctuations. We perform a standard χ 2 -minimization procedure between theoretical expectations and data, followed by a joint likelihood analysis and we find a value of γ = 0.56 ± 0.05, perfectly consistent with the expectations of the ΛCDM model, and Ω m0 = 0.29 ± 0.01, in very good 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 ∼ 0.09γ. Finally, allowing γ to vary with redshift in two manners (Taylor expansion around z = 0, and Taylor expansion around the scale factor), we find that the combined statistical analysis between our clustering and literature growth data alleviates the degeneracy and obtain more stringent constraints with respect to other recent studies.

Growth index of matter perturbations in the light of Dark Energy Survey

“…The second result is that the differences of the bias models are absorbed in the fitted value of the DM halo mass in which LRGs live, and which ranges from ∼ 6.2 × 10 12 h −1 M ⊙ − 1.2 × 10 13 h −1 M ⊙ , for the different bias models and in the case of DESY1COSMO bias. As it can also be seen from Table II, our derived mass of the host DM halo mass is consistent with that of Papageorgiou et al [61], while Sawangwit et al [62] and Pouri et al [63] found M h ≃ (1.9 − 2) × 10 13 h −1 M ⊙ . FIG.…”

Comparison of the linear bias models in the light of the Dark Energy Survey

“…The corresponding weighted mean and the combined weighted standard deviation of the DM halo mass are: Table 3. Results of the χ 2 minimization procedure using the LRGs ACF of 2SLAQ (see Sawangwit et al 2011 and Table 1 in Pouri et al 2014). In this case we have ∆AIC ≃ 0.…”

“…In the context of TRK and BPR bias models within the Planck (TT+lowP+lensing) and the DES/Planck/JLA/BAO cosmology respectively, it is interesting to mention that rescaled bias data provide an LRG host DM halo mass consistent at ∼ 2σ level with that of Sawangwit et al (2011), namely M h ≃ 2(±0.1) × 10 13 h −1 M⊙ (see also Pouri, Basilakos & Plionis et. al.…”

Background history and cosmic perturbations for a general system of self-conserved dynamical dark energy and matter

“…For the ΛCDM we have γ 6/11 0.545, and one typically expects γ(0) = 0.56 ± 0.05 for ΛCDM-like models [66]. The growth index can obviously be reexpressed as…”