Correcting for Blending Problems in Gravitational Microlensing Events by Using Hubble Space Telescope

摘要

The largest uncertainty in determining microlensing parameters arises from the blending of source star images that occurs because current experiments are being carried out toward very dense star fields, the Galactic bulge and Magellanic Clouds. Experiments attempt to correct the blending effects for individual events by introducing an additional lensing parameter, the residual flux, but this method suffers from very large uncertainties in the derived lensing parameters due to degeneracies among the parameters. In this paper, I propose to use the Hubble Space Telescope (HST) to correct blending effects. With the high resolving power of the HST, combined with color information from ground-based observations, one can uniquely identify the lensed source star in the blended seeing disk, and thus the uncertainty in the derived timescale can be significantly reduced.