Spatial matter density mapping of the STAGES Abell A901/2 supercluster field with 3D lensing

TL;DR

This study uses advanced 3D lensing techniques with HST data to map the matter distribution in the Abell 901/902 supercluster, revealing detailed structures and their relation to luminous matter, while analyzing the limitations of 3D lensing resolution.

Contribution

The paper introduces improved 3D lensing mapping methods that calibrate redshift bias and account for radial elongation, along with the first detailed noise analysis for such maps.

Findings

Mass peaks >3σ have luminous counterparts

Structures behind foreground supercluster are identified

Only the most massive structures can be resolved in 3D with current data

Abstract

We present weak lensing data from the HST/STAGES survey to study the three-dimensional spatial distribution of matter and galaxies in the Abell 901/902 supercluster complex. Our method improves over the existing 3D lensing mapping techniques by calibrating and removing redshift bias and accounting for the effects of the radial elongation of 3D structures. We also include the first detailed noise analysis of a 3D lensing map, showing that even with deep HST quality data, only the most massive structures, for example M200>~10^15 Msun/h at z~0.8, can be resolved in 3D with any reasonable redshift accuracy (\Delta z~0.15). We compare the lensing map to the stellar mass distribution and find luminous counterparts for all mass peaks detected with a peak significance >3\sigma. We see structures in and behind the z=0.165 foreground supercluster, finding structure directly behind the A901b cluster at z~0.6 and also behind the SW group at z~0.7. This 3D structure viewed in projection has no significant impact on recent mass estimates of A901b or the SW group components SWa and SWb.