Xinyi Guo, Ann Esin, Rosanne Di Stefano, Jeffrey Taylor
Gravitational microlensing events provide a potentially powerful tool for the
study of stellar populations. In particular, they can be used to discover and
study a variety of binary systems. A large number of binary lenses have already
been found by the microlensing surveys and a few of these systems show strong
evidence of orbital motion on the timescale of the lensing event. We expect
that more of such binary lenses will be detected in the future. For binaries
whose orbital period is comparable to the event duration, the orbital motion
can cause the lensing signal to deviate drastically from that of a static
binary lens. The most striking property of such lightcurves is the presence of
quasi-periodic features, produced as the source traverses the same regions in
the rotating lens plane. These repeated features contain information about the
orbital period of the lens. If this period can be extracted, a lot can be
learned about the lensing system even without performing a time-consuming
detailed lightcurve modeling. However, the relative transverse motion between
the source and the lens significantly complicates the problem of period
extraction. To resolve this difficulty, we present a modification to the
standard Lomb-Scargle periodogram analysis. We test our method for four
representative binary lens systems and demonstrate its efficiency in correctly
extracting binary orbital periods.
View original:
http://arxiv.org/abs/1112.4608
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