Nonlinear Evolution of Cosmological Structures in Warm Dark Matter Models

TL;DR

This paper investigates the nonlinear evolution of large-scale structures in warm dark matter models using both the halo model and high-resolution N-body simulations, revealing deviations from cold dark matter predictions and improving modeling accuracy.

Contribution

It combines the halo model approach with N-body simulations to better understand structure formation in warm dark matter scenarios, highlighting deviations from CDM and refining the halo model.

Findings

WDM shows a turnover in the concentration-mass relation at group scales.

WDM halo model aligns well with simulations on small scales.

Deviations from CDM suggest top-down formation processes.

Abstract

The dark energy dominated warm dark matter (WDM) model is a promising alternative cosmological scenario. We explore large-scale structure formation in this paradigm. We do this in two different ways: with the halo model approach and with the help of an ensemble of high resolution N-body simulations. Combining these quasi-independent approaches, leads to a physical understanding of the important processes which shape the formation of structures. We take a detailed look at the halo mass function, the concentrations and the linear halo bias of WDM. In all cases we find interesting deviations with respect to CDM. In particular, the concentration-mass relation displays a turnover for group scale dark matter haloes, for the case of WDM particles with masses of the order ~0.25 keV. This may be interpreted as a hint for top-down structure formation on small scales. We implement our results into the halo model and find much better agreement with simulations. On small scales the WDM halo model now performs as well as its CDM counterpart.