  The repulsion strength at the origin for repulsive/attractive potentials
determines the regularity of local minimizers of the interaction energy. In
this paper, we show that if this repulsion is like Newtonian or more singular
than Newtonian (but still locally integrable), then the local minimizers must
be locally bounded densities (and even continuous for more singular than
Newtonian repulsion). We prove this (and some other regularity results) by
first showing that the potential function associated to a local minimizer
solves an obstacle problem and then by using classical regularity results for
such problems.
