OGLE-2009-BLG-023/MOA-2009-BLG-028: Characterization of a Binary Microlensing Event Based on Survey Data

TL;DR

This study analyzes a binary microlensing event observed solely by survey data, successfully determining the lens system's physical parameters, demonstrating the potential of high-cadence surveys to characterize Galactic binaries.

Contribution

It shows that survey data alone can be used to uniquely determine physical parameters of binary microlensing events, advancing the methodology in the field.

Findings

Lens system consists of M-type dwarfs with masses 0.50 and 0.15 solar masses.

Located approximately 1.8 kpc in the Galactic disk.

Demonstrates the feasibility of routine physical parameter determination from survey data.

Abstract

We report the result of the analysis of the light curve of a caustic-crossing binary-lens microlensing event OGLE-2009-BLG-023/MOA-2009-BLG-028. Even though the event was observed solely by survey experiments, we could uniquely determine the mass of the lens and distance to it by simultaneously measuring the Einstein radius and lens parallax. From this, we find that the lens system is composed of M-type dwarfs with masses $(0.50\pm 0.07) \ M_\odot$ and $(0.15\pm 0.02)\ M_\odot$ located in the Galactic disk with a distance of $\sim 1.8$ kpc toward the Galactic bulge direction. The event demonstrates that physical lens parameters of binary-lens events can be routinely determined from future high-cadence lensing surveys and thus microlensing can provide a new way to study Galactic binaries.