  Recent observations of Reticulum II have uncovered an overabundance of
r-process elements, compared to similar ultra-faint dwarf spheroidal galaxies
(UFDs). Because the metallicity and star formation history of Reticulum II
appear consistent with all known UFDs, the high r-process abundance of
Reticulum II suggests enrichment through a single, rare event, such as a double
neutron star (NS) merger. However, we note that this scenario is extremely
unlikely, as binary stellar evolution models require significant supernova
natal kicks to produce NS-NS or NS-black hole mergers, and these kicks would
efficiently remove compact binary systems from the weak gravitational
potentials of UFDs. We examine alternative mechanisms for the production of
r-process elements in UFDs, including a novel mechanism wherein NSs in regions
of high dark matter density implode after accumulating a black-hole-forming
mass of dark matter. We find that r-process proto-material ejection by tidal
forces, when a single neutron star implodes into a black hole, can occur at a
rate matching the r-process abundance of both Reticulum II and the Milky Way.
Remarkably, dark matter models which collapse a single neutron star in observed
UFDs also solve the missing pulsar problem in the Milky Way Galactic center. We
propose tests specific to dark matter r-process production which may uncover,
or rule out, this model.
