Skewness of matter distribution in clustering dark energy cosmologies

Abstract

We calculate the skewness (the third moment S3) of matter distribution in dynamical dark energy cosmologies. We pay particular attention to the impact of dark energy perturbations on this quantity. There is indeed a clear signature of dark energy perturbations on this quantity. By properly allowing dark energy perturbations we show that their impact on S3 is strong enough (a factor ∼ 3 greater) to easily discriminate between clustering and non-clustering dark energy cosmologies. This indicates that high order statistics of the cosmic density field are useful to the study of dark energy models and are potentially able to rule out clustering dark energy cosmologies.

Skewness as a test of dark energy perturbations

“…In contrast, in this work we consider the universe as composed by two separated fluids, both of which being perturbed. As expected, we obtain now values for today's S 3 much closer to the ΛCDM case (a factor of three smaller than in [18]), in agreement therefore with standard results presented in the literature, e.g. [15] and [20].…”

“…In a previous work, [18], the universe content was modeled as a effective single fluid (an admixture of dark energy and matter), in which the dark energy contributions have been considered via the total (the single fluid realization) equation of state parameter and sound speed. In contrast, in this work we consider the universe as composed by two separated fluids, both of which being perturbed.…”

“…In previous work [18], by following the treatment used in Ref. [19], dark energy effects on S 3 have been studied by modelling the entire cosmic substratum, i.e., matter and dark energy, as a single fluid.…”

“…Now, going beyond the analysis performed in Ref. [18], we fully take into account fluctuations in both cosmological fluids using the perturbed equations up to second order for a universe composed by matter and dark energy. The dark energy density contrast acts as an independent source of the matter fluctuations.…”

Higher-order statistics of the large-scale structure from photometric redshifts

“…We demonstrated the ability of our method to accurately capture the 2-point statistics of the dark matter density, as well as its skewness and kurtosis on scales ∼ 0.04 σ z . Higher-order statistics have been promising in constraining dark energy (Velten & Fazolo 2020;Fazolo et al 2022). As we can use our method with a particle mesh, our joint inference framework can be used to constrain the bispectrum with photometric galaxy clustering.…”