NOAO >   Observing Info >   Approved Programs >   2003B-0373

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Proposal Information for 2003B-0373


PI: R. Chris Smith, NOAO/CTIO, csmith@noao.edu
Address: Cerro Tololo Inter-American Observatory, Colina El Pino S/N, La Serena, Chile

CoI: Armin Rest, NOAO/CTIO
CoI: Christopher Stubbs, University of Washington
CoI: Kem Cook, Lawrence Livermore National Laboratory
CoI: Doug Welch, McMaster University
CoI: Andrew Becker, Lucent/Bell Labs
CoI: Gajus Miknaitis, University of Washington
CoI: Stefan Keller, Lawrence Livermore National Laboratory
CoI: Sergei Nicolaev, Lawrence Livermore National Laboratory
CoI: Alejandro Clocchiatti, P. Universidad Catolica
CoI: Dante Minniti, P. Universidad Catolica
CoI: Charles Alcock, Univ. of Penn.
CoI: Suzanne Hawley, University of Washington
CoI: Ken Mighell, NOAO

Title: Spectroscopy of LMC Microlensing Events from the SuperMacho Survey

Abstract: One of the foremost outstanding problems in the physical sciences is the nature and distribution of the ``dark matter'' that is the gravitationally dominant component of mass in all galaxies, including the Milky Way. A previous experiment to search for the transient brightening of background stars due to the gravitational lensing by foreground MACHOs has produced a peculiar result: while the detected rate of lensing events indicates that MACHOs comprise at most ~20% of the dark matter halo, the number of events far exceeds that expected from known stellar populations. The nature of these excess lensing objects remains a mystery. We intend to determine the nature of this lensing population, which may outweigh all other known components of the Galaxy, by conducting a search with at least a tenfold improvement in the event detection rate. The project has been approved as an NOAO Survey program using the CTIO 4m with MOSAIC to discover microlensing events in Oct - Dec of 2001 through 2005. The major source of contamination of microlensing events in the LMC is supernovae which occur in background galaxies. We propose to use Gemini GMOS to obtain spectra to separate the microlensing events from SNe and other transient ``contaminants'' and obtain important information on the SNe discovered (type, redshift, and age).


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