The dark matter environment of the Abell 901/902 supercluster: a weak lensing analysis of the HST STAGES survey

TL;DR

This study uses high-resolution weak lensing from space-based HST data to map dark matter in the Abell 901/902 supercluster, revealing detailed substructures and their relation to visible galaxies, with implications for future dark matter studies.

Contribution

It provides the first high-resolution dark matter map of the supercluster using space-based imaging, resolving substructures and comparing with ground-based results.

Findings

Dark matter distribution closely follows galaxy distribution.

Detected a dark matter extension toward an infalling X-ray group.

No variation in mass-to-light ratios across the supercluster.

Abstract

We present a high resolution dark matter reconstruction of the z=0.165 Abell 901/902 supercluster from a weak lensing analysis of the HST STAGES survey. We detect the four main structures of the supercluster at high significance, resolving substructure within and between the clusters. We find that the distribution of dark matter is well traced by the cluster galaxies, with the brightest cluster galaxies marking out the strongest peaks in the dark matter distribution. We also find a significant extension of the dark matter distribution of Abell 901a in the direction of an infalling X-ray group Abell 901alpha. We present mass, mass-to-light and mass-to-stellar mass ratio measurements of the structures and substructures that we detect. We find no evidence for variation of the mass-to-light and mass-to-stellar mass ratio between the different clusters. We compare our space-based lensing analysis with an earlier ground-based lensing analysis of the supercluster to demonstrate the importance of space-based imaging for future weak lensing dark matter 'observations'.