Key points are not available for this paper at this time.
The authors calculate the gravitational lensing properties of an isothermal sphere in which the singularity at the origin is replaced by a finite core and contrast this with the usual singular case. This can significantly alter the statistics of the lensing of distant quasars by both the known distribution of intervening galaxies and also by a possible distribution of "dark" galaxies, as might be predicted in biased galaxy formation models. For example, it is found that the mean angular separation predicted to result from galactic lenses can be much larger than previously estimated.
Hinshaw et al. (Tue,) studied this question.