MACHO Project Analysis of the Galactic Bulge Microlensing Events with Clump Giants as Sources
We present preliminary results of the analysis of 5 years of MACHO data on the Galactic bulge microlensing events with clump giants as sources. This class of events allows one to obtain robust conclusions because relatively bright clump stars are not strongly affected by blending. We discuss: (1) the selection of ''giant'' events, (2) the distribution of event durations, (3) the anomalous character of event durations and optical depth in the MACHO field 104 centered on (l,b) = (3{sup o}.1,-3{sup o}.0). We report the preliminary average optical depth of {tau} = (2.0 {+-} 0.4) x10{sup -6} (internal) at (l,b) = (3{sup o}.9, -3{sup o}.8), and present a map of the spatial distribution of the optical depth. When field 104 is removed from the sample, the optical depth drops to {tau} = (1.4 {+-} 0.3) x 10{sup -6}, which is in excellent agreement with infrared-based models of the central Galactic region.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 15004803
- Report Number(s):
- UCRL-JC-147584; TRN: US200321%%87
- Resource Relation:
- Conference: Astrophysical Ages and Time Scales, Hilo, HI (US), 02/05/2001--02/09/2001; Other Information: ASP Conference Series, Vol. TBD, 2001 Von Hippel, Manset, Simpson eds.; PBD: 6 Mar 2002
- Country of Publication:
- United States
- Language:
- English
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