Model astrometric blending and detectability for luminous lenses

Develop a more careful treatment of astrometric microlensing events involving luminous lenses by characterizing how blending with the lens and neighboring stars, their flux ratios and angular separations, and Gaia’s scan-result and astrometric-pipeline processing affect event detectability.

Background

The paper’s detectability analysis does not fully model blending between the lensed source, a luminous lens, and neighboring stars. Gaia may resolve the components separately, report a position near the photocentre or one of the components, or fail to produce a usable astrometric measurement because of spurious detections, rejected transits, failed crossmatches, or outliers. The treatment depends on complex instrumental and pipeline effects, and the astromet package used in the study simplifies this by placing every data point at the photocentre.

Consequently, the authors explicitly defer a more realistic treatment of astrometric events with luminous lenses and the determination of their detectability. Such modelling is important because blending can alter both the observed astrometric signal and the reliability of candidate selection, particularly in crowded fields.