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B. S. Gaudi (IAS)
Determination of the frequency of planets in environments different from the local neighborhood, such as the Galactic bulge, may provide clues to the origin of planets. There are three currently feasible methods of detecting planetary companions to stars in the bulge: gravitational microlensing, transit, and "direct" detection. Microlensing searches for planets have been ongoing for six years, and have yielded interesting constraints on the frequency of Jupiter-mass planets around typical stars in the bulge (M-dwarfs) with separations 1~{\rm AU} \la a \la 5~{\rm AU}. If continued, such searches should eventually result in detections. Detecting bulge planets via transits requires a campaign of least 10 nights on a 10m-class telescope at an excellent site. Such a campaign would detect 5-50 Jupiter-size planets with a\la 0.1~{\rm AU}, if the frequency of planets in the bulge is similar to that locally. As a consistency check, close-in giant planetary companions can also be "directly" detected in caustic crossing binary-lens events, where the reflected light of the planet can be magnified by two orders of magnitude. Direct detection requires a few hours of intensive monitoring per binary-lens microlensing light curve using a 10m-class telescope. Combining these methods may eventually yield a complete census of Jovian companions to stars in the bulge with separations 0.01-10~AU. With a larger investment in observing resources, this range could plausibly be extended to \ga 20~{\rm AU}.
The author(s) of this abstract have provided an email address for comments about the abstract: gaudi@sns.ias.edu