A generalized model for gravitational microlensing of stars: Analysis of the OGLE data
Abstract
The effect of the annual parallactic displacement of a star with finite angular size and a given linear limbdarkening law on the star's microlensing light curve is examined. For some combinations of parameters, the parallactic displacement can give rise to asymmetry in the lensing curve and affect the identification of microlensing events. A procedure for the selection of a generalized, nonlinear model for this phenomenon with separate determination of the photometric and geometric parameters of the problem is proposed. This procedure makes it possible to derive from an observed lensing curve estimates of the angular diameter of the star, the parameters of the relative motion of the lens and star, and the difference in the annual parallaxes of the lens and the star in units of the Einstein cone radius. Knowledge of any one of these parameters, in turn, enables determination of the angular radius of the Einstein cone of the gravitational lens. The question of estimating the confidence limits for the model parameters is discussed. Analysis of the microlensing curve for the bulge star OGLE5 shows that the model can fit the experimental data if the gravitational lens candidate is a K5 dwarf.
 Publication:

Astronomy Reports
 Pub Date:
 January 1998
 Bibcode:
 1998ARep...42...81B