X-Ray And Optical Flux Ratio Anomalies In Quadruply Lensed Quasars. II.
  Mapping the Dark Matter Content in Elliptical Galaxies
  We present a microlensing analysis of 61 Chandra observations of 14 quadruply
lensed quasars. X-ray flux measurements of the individual quasar images give a
clean determination of the microlensing effects in the lensing galaxy and thus
offer a direct assessment of the local fraction of stellar matter making up the
total integrated mass along the lines of sight through the lensing galaxy. A
Bayesian analysis of the ensemble of lensing galaxies gives a most likely local
stellar fraction of 7%, with the other 93% in a smooth, dark matter component,
at an average impact parameter R_c of 6.6 kpc from the center of the lensing
galaxy. We divide the systems into smaller ensembles based on R_c and find that
the most likely local stellar fraction varies qualitatively and quantitatively
as expected, decreasing as a function of R_c.
