NOAO >   Observing Info >   Approved Programs >   2010B-0596

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Proposal Information for 2010B-0596


PI: Rachael L. Beaton, University of Virginia, rlb9n@virginia.edu
Address: Department of Astronomy, 530 McCormick Road, Charlottesville, Va 22904, USA

CoI: Steven R. Majewski, University of Virginia
CoI: Richard J Patterson, University of Virginia
CoI: Puragra Guhathakurta, UC-Santa Cruz
CoI: Jason Kalirai, STSci
CoI: James Bullock, UC-Irvine
CoI: Erik Tollerud, UC-Irvine
CoI: Joe Wolf, UC-Irvine

Title: Completing the SPLASH Survey of M31 dSphs

Abstract: Dwarf spheroidal (dSph) galaxies are important laboratories for testing cosmological models on the smallest scales, where (lambda)CDM has serious difficulties. Mass modeling has revealed that the nineteen explored MW dSphs have a mass of 10^7$M_\odot within their inner 300pc, despite spanning >$10^4 factor in luminosity, which suggests either a low mass threshold for star formation or a low-mass limit on DM halos. However, the first six M31 dSphs studied appear to be more extended than MW dSphs of the same luminosity. Whether this is spurious and due to either small number statistics or observational bias or a true indication of cosmological variation in subhalo formation or feedback processes in small galaxies can only be tested by improving our sampling of the M31 satellite system more equally to that of the MW system. The Spectroscopic and Photometric Landscape of the Andromeda Stellar Halo (SPLASH) collaboration has been systematically, efficiently and uniformly probing the masses and structures of M31 dSphs using its proven approach combining KPNO4-m MOSAIC imaging with Keck+DEIMOS spectroscopy and a careful five-criterion membership analysis. We propose to complete the photometric portion of our study of M31 dSphs which is needed for spectroscopic target selection and structural parameters determination.


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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