Levitating Dark Matter
  A sizable fraction of the total energy density of the universe may be in
heavy particles with a net dark $U(1)'$ charge comparable to its mass. When the
charges have the same sign the cancellation between their gravitational and
gauge forces may lead to a mismatch between different measures of masses in the
universe. Measuring galactic masses by orbits of normal matter, such as galaxy
rotation curves or lensing, will give the total mass, while the flows of dark
matter agglomerates may yield smaller values if the gauge repulsion is not
accounted for. If distant galaxies which house light beacons like SNe Ia
contain such dark particles, the observations of their cosmic recession may
mistake the weaker forces for an extra `antigravity', and infer an effective
dark energy equation of state smaller than the real one. In some cases,
including that of a cosmological constant, these effects can mimic $w<-1$. They
can also lead to a {\it local} variation of galaxy-galaxy forces, yielding a
larger `Hubble Flow' in those regions of space that could be taken for a
dynamical dark energy, or superhorizon effects.
