KMT-2019-BLG-1715: planetary microlensing event with three lens masses and two source stars

TL;DR

This paper analyzes a complex gravitational microlensing event revealing a planetary-mass object and a binary star system, using a novel method to resolve degeneracies and confirm the lens composition.

Contribution

It introduces a new approach to resolve degeneracies in microlensing events involving multiple sources and lenses, identifying a planetary-mass object within a three-body lens system.

Findings

The lens system includes a planet of about 2.6 Jupiter masses.

The system consists of a planet and binary stars in the galactic disk.

A method was developed to distinguish flux ratios between sources and lens components.

Abstract

We investigate the gravitational microlensing event KMT-2019-BLG-1715, of which light curve shows two short-term anomalies from a caustic-crossing binary-lensing light curve: one with a large deviation and the other with a small deviation. We identify five pairs of solutions, in which the anomalies are explained by adding an extra lens or source component in addition to the base binary-lens model. We resolve the degeneracies by applying a method, in which the measured flux ratio between the first and second source stars is compared with the flux ratio deduced from the ratio of the source radii. Applying this method leaves a single pair of viable solutions, in both of which the major anomaly is generated by a planetary-mass third body of the lens, and the minor anomaly is generated by a faint second source. A Bayesian analysis indicates that the lens comprises three masses: a planet-mass object with $\sim 2.6~M_{\rm J}$ and binary stars of K and M dwarfs lying in the galactic disk. We point out the possibility that the lens is the blend, and this can be verified by conducting high-resolution followup imaging for the resolution of the lens from the source.