X-ray binaries are a fascinating class of astrophysical objects. They tend to be highly variable over both short and long time scales, and can experience sudden flares and long intervals of quiescence. Several physical phenomena, including eclipses, can produce periodic behavior. It has even been hypothesized that some X-ray binaries are orbited by planets. If this is the case, dips in the observed X-ray emission may occur. Here we report on our study of archived Chandra data from several hundred X-ray sources in the galaxies M51, M101, and M104. We analyzed the data by searching for interesting time signatures in the light curves of the X-ray sources, most of which are X-ray binaries, and have found flares, dips, and periodic signatures. We present the results and consider their implications, including the prospects for planet detection and for the search of X-ray triples. This research was made possible by the SAO REU program and is funded in part by the National Science Foundation REU and Department of Defense ASSURE programs.
