OGLE-2007-BLG-224L: Confirmation of Terrestrial Parallax

TL;DR

This study uses adaptive optics imaging to set limits on the lens flux of OGLE-2007-BLG-224, confirming it as a brown dwarf and providing the first AO confirmation of a sub-stellar microlens based on terrestrial parallax.

Contribution

It presents the first adaptive optics confirmation of a sub-stellar microlens and tests a prediction based on terrestrial microlens parallax effect.

Findings

No new sources detected at the expected lens position.

Upper limit on lens flux is H>20.57.

Supports the lens being a brown dwarf.

Abstract

We present limits on the lens flux of OGLE-2007-BLG-224 based on MagAO imaging taken seven years after the microlensing event. At the time of the observations, the lens should have been separated from the microlensing source by 292 mas. However, no new sources are detected with MagAO. We place an upper limit on the lens flux of $H>20.57$. This measurement supports the conclusion of Gould et al. (2009) that the lens in this event should be a brown dwarf. This is the first test of a prediction based on the terrestrial microlens parallax effect and the first AO confirmation of a sub-stellar/dark microlens.