Abstract:

I will present a high resolution dark matter reconstruction of the z=0.165 Abell 901/902 supercluster from a weak lensing analysis of the STAGES HST survey. The dark matter map shows the four main structures of the supercluster resolved at high significance, allowing us to detect substructure within and between the clusters. I will show how 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. I will also compare the dark matter distribution to the hot gas in the cluster, showing a significant extension of the dark matter distribution of Abell 901a in the direction of an infalling X-ray group. Comparing this space-based lensing analysis with an earlier ground-based lensing analysis of the supercluster demonstrates the great importance of space-based imaging for future weak lensing dark matter 'observations'.