Q2237+0305 source structure and dimensions from light curves simulation

摘要

Assuming a two-component quasar structure model consisting of a centralcompact source and an extended outer feature, we produce microlensingsimulations for a population of star-like objects in the lens galaxy. Such amodel is a simplified version of that adopted to explain the brightnessvariations observed in Q0957 (Schild & Vakulik 2003). The microlensing lightcurves generated for a range of source parameters were compared to the lightcurves obtained in the framework of the OGLE program. With a large number oftrials we built, in the domain of the source structure parameters, probabilitydistributions to find "good" realizations of light curves. The values of thesource parameters which provide the maximum of the joint probabilitydistribution calculated for all the image components, have been accepted asestimates for the source structure parameters. The results favour thetwo-component model of the quasar brightness structure over a single compactcentral source model, and in general the simulations confirm the Schild-Vakulikmodel that previously described successfully the microlensing and otherproperties of Q0957. Adopting 3300 km/s for the transverse velocity of thesource, the effective size of the central source was determined to be about2x10^15 cm, and Epsilon =2 was obtained for the ratio of the integralluminosity of the outer feature to that of the central source.