Detections of Planets in Binaries Through the Channel of Chang-Refsdal Gravitational Lensing Events

TL;DR

This paper explores how Chang-Refsdal gravitational lensing events can serve as an effective method to detect planets in binary star systems, especially through analyzing anomalies in high-magnification light curves.

Contribution

It demonstrates that dense, high-precision observations of C-R lensing anomalies can reveal the presence of planets in both close and wide binary systems, expanding detection channels.

Findings

Analysis of OGLE-2015-BLG-1319 confirms planet detection potential.

C-R lensing anomalies can indicate planets in binary systems.

High-precision, dense coverage improves detection constraints.

Abstract

Chang-Refsdal (C-R) lensing, which refers to the gravitational lensing of a point mass perturbed by a constant external shear, provides a good approximation in describing lensing behaviors of either a very wide or a very close binary lens. C-R lensing events, which are identified by short-term anomalies near the peak of a high-magnification lensing light curves, are routinely detected from lensing surveys, but not much attention is paid to them. In this paper, we point out that C-R lensing events provide an important channel to detect planets in binaries, both in close and wide binary systems. Detecting planets through the C-R lensing event channel is possible because the planet-induced perturbation occurs in the same region of the C-R lensing-induced anomaly and thus the existence of the planet can be identified by the additional deviation in the central perturbation. By presenting the analysis of the actually observed C-R lensing event OGLE-2015-BLG-1319, we demonstrate that dense and high-precision coverage of a C-R lensing-induced perturbation can provide a strong constraint on the existence of a planet in the wide range of the planet parameters. The sample of an increased number of microlensing planets in binary systems will provide important observational constraints in giving shape to the details of the planet formation scenario which has been restricted to the case of single stars.