Interpretation of Strong ShortTerm Central Perturbations in the Light Curves of ModerateMagnification Microlensing Events
Abstract
To improve the planet detection efficiency, current planetary microlensing experiments are focused on highmagnification events searching for planetary signals near the peak of lensing light curves. However, it is known that central perturbations can also be produced by binary companions and thus it is important to distinguish planetary signals from those induced by binary companions. In this paper, we analyze the light curves of microlensing events OGLE2007BLG137/MOA2007BLG091, OGLE2007BLG355/MOA2007BLG278, and MOA2007BLG199/OGLE2007BLG419, for all of which exhibit shortterm perturbations near the peaks of the light curves. From detailed modeling of the light curves, we find that the perturbations of the events are caused by binary companions rather than planets. From a close examination of the light curves combined with the underlying physical geometry of the lens system obtained from modeling, we find that the short timescale causticcrossing feature occurring at a low or a moderate base magnification with an additional secondary perturbation is a typical feature of binarylens events and thus can be used for the discrimination between the binary and planetary interpretations.
 Publication:

The Astrophysical Journal
 Pub Date:
 November 2009
 DOI:
 10.1088/0004637X/705/2/1116
 arXiv:
 arXiv:0911.5581
 Bibcode:
 2009ApJ...705.1116H
 Keywords:

 gravitational lensing;
 planetary systems;
 Astrophysics  Earth and Planetary Astrophysics
 EPrint:
 17 pages, 4 figures, 1 table