http://arxiv.org/abs/astro-ph/0602519 Authors: H. Balasin, D. Grumiller Comments: 11 pages revtex4, 4 eps figures Report-no: LU-ITP 2006/002 Exact stationary axially symmetric solutions of the 4D Einstein equations with co-rotating pressureless perfect fluid sources are studied. This is of physical relevance for the dynamics of galaxies and questions concerning dark matter. A particular solution with approximately flat rotation curve is discussed in some detail. We find that simple Newtonian arguments over-estimate the amount of matter needed to explain these curves by more than 30%.
That's very interesting. Basically, they've done an analysis similar to that of Cooperstock and Tieu (the "GR accounting for dark matter" folks), but avoiding all of the "exotic matter" and "singular disk" problems. They find that GR effects can account for a small (~30 percent), but non-negligible, fraction of the dark matter. I must admit, it's still surprising to me that GR would be necessary at all in this limit, but I find this result to be much more plausible than the Cooperstock one.
Agreed, ST. It is a plausible approach. However, I question how well it would work with large scale structures.