http://arxiv.org/abs/1910.01105
In this paper, we quantify non-linear effects from $k$-essence dark energy through an effective parameter $\mu$ that encodes the additional contribution of a dark energy fluid or a modification of gravity to the Poisson equation. This is a first step toward quantifying the non-linear effects of dark energy/modified gravity models in a more general approach. We compare our simulation results with predictions from the linear Boltzmann code $\texttt{CLASS}$. We show that for a large $k$-essence speed of sound the $\texttt{CLASS}$ results are sufficiently accurate, while for a low speed of sound non-linearities in matter and in the $k$-essence field are non-negligible. We propose a $\tanh$-based parameterisation for $\mu$ to include the non-linear effects based on the simulation results and this parametric form of $\mu$ can be used to improve Fisher forecasts or Newtonian $N$-body simulations for $k$-essence models.
F. Hassani, B. L’Huillier, A. Shafieloo, et. al.
Thu, 3 Oct 19
24/59
Comments: 16 pages, 8 figures