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Session 7 - Microlensing.
Display session, Monday, June 08
Atlas Ballroom,
The MACHO Project is a search for dark matter in the form of massive compact halo objects (MACHOs). Photometric monitoring of tens of millions of stars in the Large Magellanic Cloud (LMC), Small Magellanic Cloud (SMC), and Galactic bulge is used to search for these rare gravitational microlensing events caused by these otherwise invisible objects. An analysis of 4 years of LMC data on 12 million stars and 5 years of SMC data on 3 million stars is currently underway. We present preliminary results of this analysis which reveal about 15 candidate microlensing events in the LMC and 1 event in the SMC. We also present our microlensing detection efficiency calculation pipeline. The accurate determination of our detection efficiency is key in estimating the MACHO contribution to the dark matter in the halo. The efficiency pipeline uses data from the MACHO Project's ground based survey and from HST observations of MACHO fields to determine the true color and luminosity distribution of LMC source stars. Artificial microlensing events are then inserted into the underlying source distribution, image sequences are created from a wide sample of real image conditions and detection efficiencies are determined using our standard reduction pipeline. The full calculation of our efficiencies requires the creation, reduction and analysis of 322 Gbytes of artificial image data and is currently underway.
