OGLE-2016-BLG-1093Lb: A Sub-Jupiter-mass Spitzer Planet Located in Galactic Bulge

TL;DR

This paper reports the measurement of a sub-Jupiter-mass planet in the Galactic bulge via microlensing, demonstrating the effectiveness of the 'cheap-space parallax' method and analyzing systematics in the light curve.

Contribution

It provides the first direct mass and distance measurements of a planetary system in the Galactic bulge using Spitzer microlensing data, validating the 'cheap-space parallax' approach.

Findings

The planet has a mass between 0.59 and 0.87 Jupiter masses.

The system is located approximately 8.1 kpc away in the Galactic bulge.

The 'cheap-space parallax' method yields consistent results for high-magnification events.

Abstract

OGLE-2016-BLG-1093 is a planetary microlensing event that is part of the statistical $Spitzer$ microlens parallax sample. The precise measurement of the microlens parallax effect for this event, combined with the measurement of finite source effects, leads to a direct measurement of the lens masses and system distance: $M_{\rm host} = 0.38$--$0.57\, M_{\odot}$, $m_p = 0.59$--$0.87\, M_{\rm Jup}$, and the system is located at the Galactic bulge ($D_L \sim 8.1$ kpc). Because this was a high-magnification event, we are also able to empirically show that the "cheap-space parallax" concept Gould & Yee (2012) produces well-constrained (and consistent) results for $|\pi_{\rm E}|$. This demonstrates that this concept can be extended to many two-body lenses. Finally, we briefly explore systematics in the $Spitzer$ light curve in this event and show that their potential impact is strongly mitigated by the color-constraint.