NOAO >   Observing Info >   Approved Programs >   2009B-0433

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Proposal Information for 2009B-0433


PI: Shannon Patel, UCSC, patel@ucolick.org
Address: Astronomy Department, 1156 High St., Santa Cruz, CA 95064

CoI: Bradford Holden, UCSC
CoI: Garth Illingworth, UCSC
CoI: Daniel Kelson, OCIW

Title: The Environmental Dependence of Star Formation Rates in the Outskirts of Galaxy Clusters at z=0.8

Abstract: Galaxy clusters will grow in mass by a factor of ~ 3 between z ~ 1 and z=0 by accreting infalling galaxies and groups of galaxies from the field. Over this redshift range, galaxies in cluster cores are predominantly non-star-forming ellipticals and S0s, while galaxies in the field are star-forming spirals. Recent work suggests that the properties of the infalling galaxies from the field will transform in the intermediate density regions found in the outskirts of clusters. With a low-dispersion prism in the IMACS spectrograph at Magellan, we have assembled a large membership list of ~ 2500 galaxies in these dynamic environments around \rxj and \ms, both at z ~ 0.8. We propose to image infalling galaxies in the outskirts of these two massive clusters in \Ufil and \Bfil-band with MOSAIC in order to derive un-obscured star formation rates as low as ~ 0.5 \sfr from the UV continuum. Our goal is to assess the impact of the local environment in the cluster outskirts in regulating star formation and evolving galaxies prior to virialization in the cluster cores. When combined with available GALEX NUV and Spitzer MIPS 24 \micron data, the \Ufil\Bfil\ imaging will provide a comprehensive view of star formation for a large sample of galaxies in diverse environments at z ~ 0.8.


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