Non-Parametric Analysis for the Dark Matter Density Evolution

TL;DR

This study tests whether the standard dark matter density evolution law holds by reconstructing a deviation function using multiple cosmological data sets, finding no significant deviation within 2 sigma confidence level.

Contribution

It introduces a model-independent method to reconstruct the dark matter density evolution deviation function without assuming a specific form.

Findings

No significant deviation from standard law within 2 sigma

Method applicable to various cosmological data sets

Supports the standard dark matter evolution model

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 $\rho_{dm} = \rho_{dm,0}(1+z)^3f(z)$, and searching the presence of any deviation ($f(z)\neq 1$). As one may see, $f(z)$ 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 $f(z)$ 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 $f(z)=1$, the standard model scenario, within $2\sigma$ c.l. in all the considered cases.