Mesolensing Explorations of Nearby Masses: From Planets to Black Holes

Nearby masses can have a high probability of lensing stars in a distant background field. This high-probability lensing, or mesolensing, can be used to dramatically increase our knowledge of dark and dim objects in the solar neighborhood, where it can discover and facilitate the study of members of the local dark matter population (free-floating planets, low-mass dwarfs, white dwarfs, neutron stars, and stellar-mass black holes). We can measure the mass and transverse velocity of those masses discovered (or already known) and determine whether or not they are in binaries with dim companions. Here we explore these and other applications of mesolensing, including the study of forms of matter that have been hypothesized but not discovered, such as intermediate-mass black holes, dark matter objects free-streaming through the Galactic disk, and planets in the outermost regions of the solar system. In each case we discuss the feasibility of deriving results based on present- day monitoring systems, and we also consider the vistas that will open with the advent of all-sky monitoring in the era of Pan-STARRS and LSST.