"Solving the Puzzles Posed by Planetary Microlensing"

Planetary microlensing surveys are beginning to produce a large haul of cold exoplanets that are difficult or impossible to detect by other methods, including large populations of Jupiters orbiting M-dwarfs and free-floating planets. As is often the case with exploratory surveys, these results are raising more questions than they answer: far too few of the discovered planets seem to be in the Galactic bulge, and there seems to be far more mass held in free-floating planets than all forms of bound planets. I will review the insights into cold exoplanet populations that gravitational microlensing surveys are providing, before outlining how current and future experiments can address the questions raised, with a focus on combined ground-and-space microlensing parallax surveys such as the ongoing K2 Campaign 9 and DECam's important role in it.