From Eric's Wiki

Sand07 separate the baryons from the dark matter using galaxy dynamics and lensing. They look at MS2137-23 and Abell 383, both relaxed cooling-flow systems. When they talk about baryonic content, they mean only the galactic content which might be correct for the inner region they focus on. No mention of x-ray data is made. In any case, they find a shallow β = 0.5 ± 0.2 DM profile for A0383 but can't fit MS2137-23.

Massey07 is a nice paper. They created a map of the dark matter in the COSMOS field and then, and here's the clever part, constructed a map of the baryon content with the baryon content weighted to correct for the different sensitivity of the lensing and baryon probes as a function of redshift. For example, x-rays fall off as r^{^-2} while lensing is most sensitive to matter at half the distance to the source.

Bibliography

• Massey07: Massey et al Nature 445 286, 18 January 2007
• Sand07: Sand, True, Ellis, Simth, & Kneib, 0710.1069