NOAO >   Observing Info >   Approved Programs >   2002B-0320

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Proposal Information for 2002B-0320


PI: Mike Hudson, U Waterloo, mjhudson@uwaterloo.ca
Address: 200 University Ave W, Waterloo, Ontario N2L 3G1, Canada

CoI: Laura Parker, U Waterloo
CoI: Ray Carlberg, U Toronto
CoI: Henk Hoekstra, U Toronto/CITA
CoI: David Schade, HIA/CADC

Title: Weak Lensing by Galaxy Groups

Abstract: Galaxy groups dominate the mass density of the Universe, yet their mass-to-light ratios and dark matter profiles are poorly understood in comparison with galaxies or rich clusters. We have recently used the CNOC2 redshift survey to produce a catalogue of intermediate-redshift groups. The dynamical analysis suggests that the mass-to-light profile of galaxy groups rises by a factor of three to ten across their virialized extent. This unique dynamical sample is optimal for weak lensing studies by virtue of its median redshift (z ~ 0.4) and sky coverage (0.5 square degrees). We have nearly completed a weak lensing survey of CNOC2 fields to test the dynamical results and extend the mass profile measurement beyond the virialized regime, where dynamical methods fail. In this proposal, we demonstrate that these observations will give a \ge 5 \sigma detection of the rise in M/L with radius. The data will also be used to investigate galaxy-galaxy lensing and the morphological dependence of galaxy evolution in these groups. From the CFH12k data we have nearly-complete data for 3 of the 4 CNOC2 fields. However, in 2002B installation and commissioning of MegaCam is scheduled for the dates we require. In this proposal, we request 2 nights from the KPNO 4m+MOSAIC to complete the weak lensing survey by obtaining data for the 0223+05 field and completing observations of the 0920+37 field.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



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