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.
Highlights
Our current understanding of cosmology describes an intricate web of dark matter spanning the Universe dictating when and where galaxies form
We have reviewed the theory presented in STH09, presented details of the extensions and new analysis tools
For readers optimising future survey designs, the most relevant results are contained in Figs. 3 and 4, which show the best 3D mass resolution that can be attained on the considered angular scales with space-based quality data with a galaxy number density of 65 galaxies per square arcmin matched by 10 galaxies per square arcmin with groundbased photometric redshift estimates with a redshift error of σz/(1 + z) = 0.02
Summary
Our current understanding of cosmology describes an intricate web of dark matter spanning the Universe dictating when and where galaxies form. These large-scale structures of dark matter have long been simulated in large N-body computations (Springel 2005), but due to the nature of dark matter, linking this feature of dark matter theory directly to observations has been a challenging task. The dark matter density is inferred from the break-scale in the galaxy power spectrum, and by combining fluctuations in the cosmic microwave background, the luminosity-density relation of supernovae Type Ia, the Lyman-α forest, or the bulk motions of galaxies. A direct detection of dark matter particles as such is still an open issue
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