Testing deviations from ΛCDM with growth rate measurements from six large-scale structure surveys atz= 0.06–1

Abstract

We use measurements from the Planck satellite mission and galaxy redshift surveys over the last decade to test three of the basic assumptions of the standard model of cosmology, ΛCDM: the spatial curvature of the universe, the nature of dark energy and the laws of gravity on large scales. We obtain improved constraints on several scenarios that violate one or more of these assumptions. We measure w 0 = −0.94 ± 0.17 (18% measurement) and 1 + w a = 1.16 ± 0.36 (31% measurement) for models with a time-dependent equation of state, which is an improvement over current best constraints (Aubourg et al. 2014). In the context of modified gravity, we consider popular scalar tensor models as well as a parametrization of the growth factor. In the case of one-parameter f (R) gravity models with a ΛCDM background, we constrain B 0 < 1.36 × 10 −5 (1σ C.L.), which is an improvement by a factor of 4 on the current best (Xu 2015). We provide the very first constraint on the coupling parameters of general scalar-tensor theory and stringent constraint on the only free coupling parameter of Chameleon models. We also derive constraints on extended Chameleon models, improving the constraint on the coupling by a factor of 6 on the current best (Hojjati et al. 2011) . We also measure γ = 0.612 ± 0.072 (11.7% measurement) for growth index parametrization. We improve all the current constraints by combining results from various galaxy redshift surveys in a coherent way, which includes a careful treatment of scale-dependence introduced by modified gravity.

The linear growth of structure in theRh=ctuniverse

“…Care must be taken with the use of these data, however, because the measurements are not all completely independent (Alam et al 2016). Though based on six different (mostly independent) surveys, in some cases probing different biased tracers, they are nonetheless essentially diagnosing the same matter density field, so some of the sampled volumes overlap.…”

“…Though based on six different (mostly independent) surveys, in some cases probing different biased tracers, they are nonetheless essentially diagnosing the same matter density field, so some of the sampled volumes overlap. Alam et al (2016) have calculated the fractional overlap volume between each pair of samples, from which they then estimated the correlation between the corresponding measurements (see their figure 2). …”

“…The data plotted here have all been recalibrated for the Planck cosmology (Planck Collaboration 2014a). The solid curve shows the Planck ΛCDM prediction, based on the joint analysis of the Planck measurements and the growth rate measurements listed in Table 2, with the shaded (light-gray) band giving the 1 σ confidence region (adapted from Alam et al 2016). The χ 2 for this fit is 8.4 with 9 − 3 = 6 degrees of freedom.…”

“…The solid curve, with its associated (light-gray) 1 σ confidence region, shows the optimized ΛCDM fit based on the joint analysis of the Planck and linear growth rate data (adapted from Alam et al 2016). The χ 2 for this fit is 8.4, with 9 − 3 = 6 degrees of freedom.…”

“…of the changing growth rate as the Universe evolves (Peacock et al 2001;Viel et al 2004;Jain and Zhang 2007;Ross et al 2007;da Angela et al 2008;Guzzo et al 2008;Song and Koyama 2009;Song and Percival 2009;Davis et al 2011;Hudson and Turnbull 2012;Macaulay et al 2013;Alam et al 2016).…”