Astrophysical Constraints on Dark Energy
  Dark energy (i.e., a cosmological constant) leads, in the Newtonian
approximation, to a repulsive force which grows linearly with distance and
which can have astrophysical consequences. For example, the dark energy force
overcomes the gravitational attraction from an isolated object (e.g., dwarf
galaxy) of mass $10^7 M_\odot$ at a distance of $~ 23$ kpc. Observable
velocities of bound satellites (rotation curves) could be significantly
affected, and therefore used to measure or constrain the dark energy density.
Here, {\it isolated} means that the gravitational effect of large nearby
galaxies (specifically, of their dark matter halos) is negligible; examples of
isolated dwarf galaxies include Antlia or DDO 1903
