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Weak gravitational lensing can be combined with distance information from galaxy redshifts to great effect in 3-D weak lensing. With both shear and redshift information I show how the full 3-D dark matter distribution can be reconstructed and present a first application to the COMBO-17 data-set. In addition, I describe the Jain-Taylor geometric test, taking ratios of galaxy shear at different distances, as a probe of the dark energy in the universe and present a preliminary application to COMBO-17. To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present our cosmic shear analysis of the Galaxy Evolution from Morphology and SEDs (GEMS) survey. Imaged with the Advanced Camera for Surveys (ACS) on HST, GEMS provides high resolution imaging spanning some 800 square arcmins in the Chandra Deep Field South (CDFS). We discuss the benefits of using space-based data for weak lensing studies and show that the ACS is a very powerful instrument in this regard. We find that we are not limited by systematic errors arising from the anisotropic ACS point spread function distortion and use our cosmic shear results to place joint constraints on the matter density parameter ??m and the amplitude of the matter power spectrum ??8, finding ??8(??m/0.3)0.62=0.73 ?? 0.12.

We present a unique multiwavelength dataset of the Abell 901/902 supercluster at $z=0.16$ . The environment of the structure is well characterized by weak lensing analysis, galaxy dynamics, and X-ray imaging, and we examine how galaxy properties correlate with these measures of environment. We examine the star-formation–density relation and find a surface mass density threshold above which star-formation in supercluster galaxies is truncated, and that this transformation affects primarily the faint end of the star-forming galaxy population (down to $M^*+6$ ). In addition, we present a preliminary dynamical analysis of the spectroscopic sample ( $n\sim 300$ galaxies), revealing a bimodal distribution of galaxy velocities and significant substructure. To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html