Degeneracies in triple gravitational microlensing

We study microlensing light curves by a triple lens, in particular, by a primary star plus two planets. A four-fold degeneracy is confirmed in the light curves, similar to the close and wide degeneracy found in a double lens. Furthermore, we derive a set of equations for triple lens in the external...

Full description

Saved in:
Bibliographic Details
Published in:Monthly notices of the Royal Astronomical Society 2014-02, Vol.437 (4), p.4006-4018
Main Authors: Song, Ying-Yi, Mao, Shude, An, Jin H.
Format: Article
Language:English
Subjects:
Astronomy
Light
Planets
Citations: Items that this one cites
Items that cite this one
Online Access:Request full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:We study microlensing light curves by a triple lens, in particular, by a primary star plus two planets. A four-fold degeneracy is confirmed in the light curves, similar to the close and wide degeneracy found in a double lens. Furthermore, we derive a set of equations for triple lens in the external shear approximation. By using these external shear equations, we identify two kinds of continuous degeneracies which may be confused double and triple lenses, i.e. the continuous external shear degeneracy among triple-lens systems and the double-triple lens degeneracy. These degeneracies are particularly important in high-magnification events, and thus, some caution needs to be applied when one infers the fraction of stars hosting multiple planets from microlensing. We study the dependence of the degeneracies on the lensing parameters (e.g. source trajectory) and give recipes about how the degeneracies should be explored with real data.
ISSN:0035-8711
1365-2966
DOI:10.1093/mnras/stt2222