From John Oedemark:

Re: Where's the dark matter? Not here, befuddled astronomers find (April 18): If the dark matter is missing from this region and a new formulation of dark matter understanding is needed, then I would like to propose the following scenario.

As dark matter and dark energy are invisible, it may purely be they are particles moving faster than the speed of light. They both may be generated as matter which is visible, passes through dark central events (black holes). Travelling faster than light they generate the very medium into which the universe expands, as it slows down it becomes dark matter which can be detected in underground facilities around the world (although very infrequently). In any galaxy in the universe all matter is travelling at the speed of light or less thus giving what we can call calculable mass. The absence of dark matter/energy is due to the mass of all the objects within the "halo" of light of detectable physical mass. The Universe may be a trilogy of light in various states the major parts being dark energy followed by dark matter and finally visible light. This would explain the proportional representation of energy/matter throughout the entire universe.

In conclusion: the lack of dark matter/energy within any galaxy could be understood. Just a thought.