Did Zhao & Qin Solve the Apparant Conflict Beween Gravitational Lens   Time Delays, Dark Matter and the Hubble Constant?
  The solution proposed by Zhao & Qin to the apparent conflict between gravitational lens time delays, local estimates of the Hubble constant and current expectations for the structure of CDM halos is discussed. Two essential points emerge. First, the degeneracy is exactly the same as the local surface density degeneracy previously discussed in the literature. Second, the proposed mass distribution is inconsistent with CDM halo models. The Hubble constant is raised by making the dark matter far less centrally concentrated than predicted for CDM halos, much like the changes suggested for reconciling CDM halos with the rotation curves of dwarf and LSB galaxies. Thus, while galaxies still have dark matter, the Zhao & Qin solution to the time delay problem requires fundamental changes in the CDM paradigm for halo structure. 
C.S. Kochanek (Center for Astrophysics)