Reanalysis of the Gravitational Microlensing Event MACHO-97-BLG-41 based on Combined Data

TL;DR

This paper reanalyzes the gravitational microlensing event MACHO-97-BLG-41 using combined data, demonstrating that a binary-lens model fits better than a circumbinary planet model, highlighting the importance of dense data coverage.

Contribution

It provides a comprehensive reanalysis with combined data, favoring the binary-lens interpretation over the circumbinary planet hypothesis.

Findings

Binary-lens model fits the data better than the circumbinary planet model.

Higher-order effects are crucial for accurate interpretation.

Dense and even data coverage improves event analysis.

Abstract

MACHO-97-BLG-41 is a gravitational microlensing event produced by a lens composed of multiple masses detected by the first-generation lensing experiment. For the event, there exist two different interpretations of the lens from independent analyses based on two different data sets: one interpreted the event as produced by a circumbinary planetary system while the other explained the light curve with only a binary system by introducing orbital motion of the lens. According to the former interpretation, the lens would be not only the first planet detected via microlensing but also the first circumbinary planet ever detected. To resolve the issue using state-of-the-art analysis methods, we reanalyze the event based on the combined data used separately by the previous analyses. By considering various higher-order effects, we find that the orbiting binary-lens model provides a better fit than the circumbinary planet model with \Delta\chi^2 ~166. The result signifies the importance of even and dense coverage of lensing light curves in the interpretation of events.