Halo Properties and Mass Functions of Groups/Clusters from the DESI Legacy Imaging Surveys DR9

TL;DR

This study measures and models the weak lensing signals of galaxy groups and clusters from the DESI Legacy Imaging Surveys DR9, providing insights into their halo properties and mass functions across different redshifts and masses.

Contribution

It presents a comprehensive analysis of halo properties and mass functions using weak lensing data from a large, well-characterized group/cluster catalog, including off-centering effects.

Findings

Halo masses, bias, and concentrations are consistent across different group centers.

The model reliably describes lensing signals across various mass and redshift bins.

Halo mass functions are measured with high precision up to redshift 0.6.

Abstract

Based on a large group/cluster catalog recently constructed from the DESI Legacy Imaging Surveys DR9 using an extended halo-based group finder, we measure and model the group-galaxy weak lensing signals for groups/clusters in a few redshift bins within redshift range $0.1 \leqslant z<0.6$. Here, the background shear signals are obtained based on the DECaLS survey shape catalog derived with the \textsc{Fourier\_Quad} method. We divide the lens samples into 5 equispaced redshift bins and 7 mass bins, which allow us to probe the redshift and mass dependence of the lensing signals and hence the resulting halo properties. In addition to these sample selections, we have also checked the signals around different group centers, e.g., brightest central galaxy (BCG), luminosity weighted center and number weighted center. We use a lensing model that includes off-centering to describe the lensing signals we measure for all mass and redshift bins. The results demonstrate that our model predictions for the halo masses, bias and concentrations are stable and self-consistent among different samples for different group centers. Taking advantage of the very large and complete sample of groups/clusters, as well as the reliable estimation of their halo masses, we provide measurements of the cumulative halo mass functions up to redshift $z=0.6$, with a mass precision at $0.03\sim0.09$ dex.