Introducing OMEGA, an Emission Line Galaxy Survey in A901/902
Tim Weinzirl
University of Nottingham
Alfonso Aragon-Salamanca (Nottingham), Meghan Gray (Nottingham), Steven Bamford (Nottingham), Bruno Rodriguez (INTA-CSIC), Ana Chies-Santos (Universidade Federal do Rio Grande do Sul)
Truly understanding the role of galaxy environment on galaxy formation and evolution requires a three-dimensional analysis. Most studies of galaxies in clusters, where the environmental effects are strongest, have been carried out in two dimensions, where projection effects result in large uncertainties. These problems are greatly ameliorated in our 100-hour ESO OMEGA (OSIRIS Mapping of Emission-line Galaxies) observing campaign of the A901/2 multi-cluster system at z~0.165.

In OMEGA we target the H-alpha and [NII] emission lines over a 650 square arcminute field with the tunable filter mode of the OSIRIS instrument on GRANTECAN. By folding emission-line diagnostics, including redshifts from H-alpha, into our ongoing study of the A901/2 system, we are able to study how galaxy properties depend on a wide range of galaxy environments. I will present early results concerning how galaxy properties (star formation, black hole activity, and other global galaxy properties) differ, or not, across cluster phase space.