X-ray Monitoring of Gravitational Lenses With Chandra
  We present \emph{Chandra} monitoring data for six gravitationally lensed
quasars: QJ 0158$-$4325, HE 0435$-$1223, HE 1104$-$1805, SDSS 0924+0219, SDSS
1004+4112, and Q 2237+0305. We detect X-ray microlensing variability in all six
lenses with high confidence. We detect energy dependent microlensing in HE
0435$-$1223, SDSS 1004+4112, SDSS 0924+0219 and Q 2237+0305. We present a
detailed spectral analysis for each lens, and find that simple power-law models
plus Gaussian emission lines give good fits to the spectra. We detect intrinsic
spectral variability in two epochs of Q 2237+0305. We detect differential
absorption between images in four lenses. We also detect the \feka\ emission
line in all six lenses, and the Ni XXVII K$\alpha$ line in two images of Q
2237+0305. The rest frame equivalent widths of the \feka\ lines are measured to
be 0.4--1.2 keV, significantly higher than those measured in typical active
galactic nuclei of similar X-ray luminosities. This suggests that the \feka\
emission region is more compact or centrally concentrated than the continuum
emission region.
