OGLE-2013-BLG-0578L: Microlensing Binary Composed of A Brown Dwarf And An M Dwarf

TL;DR

This paper analyzes a microlensing event where real-time modeling allowed precise measurement of the Einstein radius, revealing a binary system with an M-dwarf and a brown dwarf, demonstrating microlensing's effectiveness in characterizing faint objects.

Contribution

It presents a method for precise parameter determination of binary microlenses using real-time analysis, identifying a brown dwarf and M-dwarf binary system.

Findings

The lens system is composed of an M-dwarf and a brown dwarf.

Real-time caustic crossing prediction improves parameter measurement.

Microlensing effectively detects faint or dark objects in the Galaxy.

Abstract

Determining physical parameters of binary microlenses is hampered by the lack of information about the angular Einstein radius due to the difficulty of resolving caustic crossings. In this paper, we present the analysis of the binary microlensing event OGLE-2013-BLG-0578, for which the caustic exit was precisely predicted in advance from real-time analysis, enabling to densely resolve the caustic crossing and to measure the Einstein radius. From the mass measurement of the lens system based on the Einstein radius combined with the additional information about the lens parallax, we identify that the lens is a binary that is composed of a late-type M-dwarf primary and a substellar brown-dwarf companion. The event demonstrates the capability of current real-time microlensing modeling and the usefulness of microlensing in detecting and characterizing faint or dark objects in the Galaxy.