A New Type of Ambiguity in the Planet and Binary Interpretations of Central Perturbations of High-Magnification Gravitational Microlensing Events

Understand

High-magnification microlensing events provide an important channel to detect planets.

• Perturbations near the peak of a high-magnification event can be produced either by a planet or a binary companion.
• It is known that central perturbations induced by both types of companions can be generally distinguished due to the basically different magnification pattern around caustics.
• In this paper, we present a case of central perturbations for which it is difficult to distinguish the planetary and binary interpretations.