Adventures in Planet Discovery in X-Ray Binaries

The first candidate planet in an external galaxy, the Whirlpool galaxy, M51, was discovered by searching for short duration X-ray transits. This method is feasible because the sizes of the X-ray emitting regions in many X-ray binaries are comparable to, or even smaller than typical sizes of planets. The transit of the X-ray source by a planet can therefore lead to a full or nearly full blocking of the X-rays. During the past nine months we have been conducting a larger scale study of X-ray sources in Chandra’s archive and Catalog. Any such search will discover dips of many types, and flares as well. We will report on several of our most interesting findings to date, focusing not only on the discoveries but also on the adventures of modeling a full complement of physical possibilities for each potential discovery.