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Exploring the Extremes of Exoplanet Detection and Characterization in High-Magnification Microlensing Events
Yee, Jennifer Chun Ming

, Doctor of Philosophy, Ohio State University, Astronomy.
The field of microlensing planet searches is about to enter a new
phase in which wide-field surveys will be the dominant mode of planet
detection. In addition, there are now plans to execute microlensing
surveys from space allowing the technique to reach smaller planets and
resolve some of difficulties of ground-based microlensing where the
resolution is poor. This new phase of observations also requires a new
mode of analysis in which events are analyzed en masse rather
than as individuals.

Until now, there has not been any investigation into the detection
threshold for planets in real data. Some people have suggested that
the threshold for detecting planets may be as small as Delta chi^2
of 160, and that is frequently used in microlensing simulations of
planet yields. However, no planets have been published with signals
that small. I have done the first empirical investigation of the
detection threshold for planets in high-magnification microlensing
events. I found that MOA-2008-BLG-310 (Delta chi^2=880),
MOA-2011-BLG-293 (Delta chi^2=500 without followup data), and
MOA-2010-BLG-311 (Delta chi^2=80) form a sequence that spans from
detected with high confidence (mb310) to marginally detected (mb293)
to something too small to claim with confidence (mb311). This suggests
that the detection threshold for planets in high-magnification events
is 500 <= Delta chi^2<880.

I have also analyzed OGLE-2008-BLG-279 to determine the range of
planets that are detectable for this event given the excellent data
quality and the high-magnification. This event illustrates that
high-magnification events will still be important in the era of
surveys because each event is much more sensitive to planets than
any individual low-magnification event. Because they probe the central
caustics, high-magnification events are sensitive to planets at any
angle, meaning that they place more stringent limits on the presence
of planets. For this event, Jupiter-mass companions can be ruled out
from 0.5-20 AU.

As the field extends to new modes of observations, it is worth
considering how we can maximize the information we can obtain for each
microlensing event, particularly given the limitation that
microlensing is primarily sensitive to mass ratio rather than planet
mass. I propose a means to take advantage of the excellent light
curves that will be available from space and combine them with
ground-based observations to measure microlens parallax for a large
fraction of the microlensing events that will be seen by a space-based
microlensing survey. This measurement will enable the measurement of
the planet masses for these events.
Andrew Gould (Advisor)
B. Scott Gaudi (Committee Member)
Richard Pogge (Committee Member)

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Yee, J. (). Exploring the Extremes of Exoplanet Detection and Characterization in High-Magnification Microlensing Events. (Electronic Thesis or Dissertation). Retrieved from https://etd.ohiolink.edu/

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Yee, Jennifer. "Exploring the Extremes of Exoplanet Detection and Characterization in High-Magnification Microlensing Events." Electronic Thesis or Dissertation. Ohio State University, . OhioLINK Electronic Theses and Dissertations Center. 10 Dec 2017.

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Yee, Jennifer "Exploring the Extremes of Exoplanet Detection and Characterization in High-Magnification Microlensing Events." Electronic Thesis or Dissertation. Ohio State University, . https://etd.ohiolink.edu/

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