MagAO observations of the binary microlens OGLE-2014-BLG-1050 prefer the higher-mass solution

TL;DR

This study uses adaptive optics imaging to resolve the degeneracy in a binary microlensing event, favoring the higher-mass solution and accurately characterizing the lens system's masses and distance.

Contribution

First AO follow-up imaging of OGLE-2014-BLG-1050 to resolve microlensing parallax degeneracy and determine the lens system's properties.

Findings

Higher-mass solution is consistent with AO flux measurements.

Lens system consists of a ~1.05 M_Sun primary and a ~0.38 M_Sun secondary.

Lens located at approximately 3.43 kpc.

Abstract

We report adaptive-optics (AO) follow-up imaging of OGLE-2014-BLG-1050, which is the second binary microlensing event with space-based parallax measurements. The degeneracy in microlens parallax pi_E led to two sets of solutions, either a ~(0.9, 0.35) M_Sun binary at ~3.5 kpc, or a ~(0.2, 0.07) M_Sun binary at ~1.1 kpc. We measure the flux blended with the microlensed source by conducting Magellan AO observations, and find that the blending is consistent with the predicted lens flux from the higher-mass solution. From the combination of the AO flux measurement together with previous lensing constraints, it is estimated that} the lens system consists of a $1.05^{+0.08}_{-0.07}$ M_Sun primary and a $0.38^{+0.07}_{-0.06}$ M_Sun secondary at $3.43^{+0.19}_{-0.21}$ kpc.