Reconciling the predictions of microlensing analysis with radial velocity measurements for OGLE-2011-BLG-0417

TL;DR

This paper revises the microlensing model for OGLE-2011-BLG-0417, resolving previous discrepancies with radial velocity data by incorporating Gaia DR2 constraints and proposing new model differentiation methods.

Contribution

It introduces a simplified, consistent microlensing model for OGLE-2011-BLG-0417 that aligns with multiple observational datasets, including Gaia DR2, and presents a novel approach to distinguish degenerate models.

Findings

Revised microlensing model agrees with radial velocity and Gaia data.

Demonstrates the importance of thorough modeling for future missions.

Proposes a new method using Gaia proper motions to differentiate models.

Abstract

Microlensing is able to reveal multiple body systems located several kilo-parsec away from the Earth. Since it does not require the measurement of light from the lens, microlensing is sensitive to a range of objects from free-floating planets to stellar black holes. But if the lens emits enough light, the microlensing model predictions can be tested with high-resolution imaging and/or radial velocity methods. Such follow-up was done for the microlensing event OGLE-2011-BLG-0417, which was expected to be a close by ($\le$ 1 kpc), low-mass ($\sim 0.8 M_\odot$) binary star with a period $P\sim 1.4$ yr. The spectroscopic follow-up observations conducted with the VLT did not measure any variation in the radial velocity, in strong contradiction with the published microlensing model. In the present work, we remodel this event and find a simpler model in agreement with all the available measurements, including the recent GAIA DR2 parallax constraints. We also present a new way to distinguish degenerate models by using the GAIA DR2 proper motions. This work stresses the importance of thorough microlensing modeling, especially with the horizon of the {\it WFIRST} and the {\it Euclid} microlensing space missions.