New catalogue of dark-matter halo properties identified in MICE-GC -- I. Analysis of density profile distributions

TL;DR

This paper presents a comprehensive catalogue of dark matter halo properties from the MICE-GC simulation, analyzing density profiles and shapes in 2D and 3D to improve weak lensing mass estimates and understand biases.

Contribution

It provides the first detailed comparison of NFW and Einasto profile fits in 2D and 3D, highlighting biases and the superiority of the Einasto model for halo characterization.

Findings

Einasto profiles fit halo density better than NFW.

Biases exist in mass and concentration estimates from 2D and 3D fits.

Biases depend on fitting range and profile model, not halo shape.

Abstract

Constraints on dark matter halo masses from weak gravitational lensing can be improved significantly by using additional information about the morphology of their density distribution, leading to tighter cosmological constraints derived from the halo mass function. This work is the first of two in which we investigate the accuracy of halo morphology and mass measurements in 2D and 3D. To this end, we determine several halo physical properties in the MICE-Grand Challenge dark matter only simulation. We present a public catalogue of these properties that includes density profiles and shape parameters measured in 2D and 3D, the halo centre at the peak of the 3D density distribution as well as the gravitational and kinetic energies and angular momentum vectors. The density profiles are computed using spherical and ellipsoidal radial bins, taking into account the halo shapes. We also provide halo concentrations and masses derived from fits to 2D and 3D density profiles using NFW and Einasto models for halos with more than $1000$ particles ($\gtrsim 3 \times 10^{13} h^{-1} M_{\odot}$). We find that the Einasto model provides better fits compared to NFW, regardless of the halo relaxation state and shape. The mass and concentration parameters of the 3D density profiles derived from fits to the 2D profiles are in general biased. Similar biases are obtained when constraining mass and concentrations using a weak-lensing stacking analysis. We show that these biases depend on the radial range and density profile model adopted in the fitting procedure, but not on the halo shape.