Fitting Photometry of Blended Microlensing Events

• Main Authors: Thomas, Christian L, Griest, Kim
• Format: Journal Article
• Language: English
• Published: 08-07-2005
• Subjects: Physics - Astrophysics of Galaxies; Physics - Cosmology and Nongalactic Astrophysics; Physics - Earth and Planetary Astrophysics; Physics - High Energy Astrophysical Phenomena; Physics - Instrumentation and Methods for Astrophysics; Physics - Solar and Stellar Astrophysics
• DOI: 10.48550/arxiv.astro-ph/0507218

Astrophys.J.640:299-307,2006 We reexamine the usefulness of fitting blended lightcurve models to
microlensing photometric data. We find agreement with previous workers (e.g.
Wozniak & Paczynski) that this is a difficult proposition because of the
degeneracy of blend fraction with other fit parameters. We show that follow-up
observations at specific point along the lightcurve (peak region and wings) of
high magnification events are the most helpful in removing degeneracies. We
also show that very small errors in the baseline magnitude can result in
problems in measuring the blend fraction, and study the importance of
non-Gaussian errors in the fit results. The biases and skewness in the
distribution of the recovered blend fraction is discussed. We also find a new
approximation formula relating the blend fraction and the unblended fit
parameters to the underlying event duration needed to estimate microlensing
optical depth.