Microlensing optical depth toward the Galactic Bulge using bright sources from OGLE-II
作者： K. Zebrun , T. Sumi , A. Udalski , B. Paczynski , G. Pietrzynski
DOI: 10.1086/497951
关键词:
摘要: We present a measurement of the microlensing optical depth toward Galactic Bulge based on 4 years OGLE-II survey using Red Clump Giant (RCG). Using 32 events we find tau=2.55_{-0.46}^{+0.57}* 10^{-6} at (l,b)=(1.16, -2.75). Taking into account measured gradient along latitude b, tau = [ (4.48+/- 2.37) + (0.78+/- 0.84)* b]* 10^{-6}, this value is consistent with previous measurements RCG sources and recent theoretical predictions. determine parameters select model light curve flux blending. that ~38% which appear to have are actually due much fainter stars blended bright companion. show explicitly fits without blending result in similar estimates through partial cancellation contributions from higher detection efficiency, underestimated time-scales larger number selected events. This approach, however, leads biased time-scale distributions event rates. Consequently, studies should carefully consider source confusion effects even for stars.
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