Gravitational microlensing by a galactic bar

Observations have found that the microlensing optical depth in the direction of the galactic center is larger than theoretical predictions. Here we investigate the effect a galactic bar has on microlensing. We use two models for the bar in order to find the range of microlensing predications. We find that sufficient optical depth in Baade's window can be attained with bars of significantly different geometries. The difference in geometry can be mapped out with the optical depths; however, this method may not be able to distinguish some bars from bulges. The time-scale distributions for different models are calculated and compared. Substantial disk microlensing may eventually be distinguishable by an extended tail in the time-scale distribution. © 1995 American Astronomical Society.