Testing Clustering Dark Energy Models With The Skewness Of Matter Distribution
Name: RAQUEL EMY FAZOLO
Publication date: 10/10/2022
Examining board:
Name |
Role |
|---|---|
| CHRISTIAN MARINONI | Examinador Externo |
| CORNELIUS RAMPF | Examinador Externo |
| HERMANO ENDLICH SCHNEIDER VELTEN | Presidente |
| LUCA AMENDOLA | Coorientador |
| OLIVER FABIO PIATTELLA | Examinador Interno |
Summary: This work aims to test clustering dark energy with the cosmological skewness, the third statistical moment of the matter density distribution. Usually, dark energy is treated as a cosmological constant or a fluid with negative pressure that has the properties to accelerate the cosmic background expansion. We start our analysis by explaining the standard treatment about dark energy, then cosmological perturbations are introduced. In general relativity it is not trivial to work with higher order perturbations so we make a transition to the Neo Newtonian cosmology, using the fluid dynamics equations that are equivalent to the general relativity ones to a good approximation. We then studied the cosmological skewness in two approaches: the single-fluid and two-fluid analysis. In the first approach, we model the universe as an effective single fluid WHERE the dark energy background contributions and perturbations are included via the total equation of state parameter. This is indeed a very simplified attempt, but this analysis was useful to provide preliminary hints about how dark energy affects the skewness of matter distribution. We then apply a more general approach, modeling the universe as two non-interacting components, pressureless matter and dark energy which is a more realistic scenario. The single fluid analysis shows a great increase in skewness when including the clustering dark energy terms. This can be explained by including the terms directly in the matter equation, not just as an additional source for the gravitational field. The two fluid model results show values around the standard cosmological ones. Tests are performed to probe the skewness dependence with the cosmological parameters. Until this work, only an expression for the skewness as a function of the matter density parameter m0 was available in the literature. We go beyond introducing several fits for the cosmological skewness value as a function of the dark energy equation of state wde and the dark energy speed of sound c2 de. This result has been presented in the literature for the first time. In order to check the consistency of our results, we finish with an observational analysis using CFHTLS-Wide data. Whereas the current available data is not enough to promote the skewness to the status of a precise cosmological test, further analysis and observations are indeed needed to make skewness a better tool to study dark energy models in the future.
