Non-parametric analysis for the dark matter density evolution

Abstract

In this paper, we investigate a potential departure in the standard dark matter density evolution law, ${\rho }_{dm}={\rho }_{dm,0}{(1+z)}^3$. The method involves considering a deformed evolution model, denoted as ${\rho }_{dm}={\rho }_{dm,0}{(1+z)}^{3}f\left(z\right)$, and searching for the presence of any deviation ($f\left(z\right)\ne 1$). As one may see, $f\left(z\right)$ is a general function that parametrizes a possible digression from the standard law. We use data of baryon acoustic oscillations, type I Supernovae luminosity distances, and galaxy cluster gas mass fraction observations to reconstruct $f\left(z\right)$ through an approach that is not dependent on the cosmological model or the so-called Gaussian process regression. Unlike previous works, it enables us to investigate a possible deviation without using a specific function to describe it. We have obtained $f\left(z\right)=1$, the standard model scenario, within $2\sigma$ c.l. in all the considered cases.