Chandra Observations of SDSS J1004+4112: Constraints on the Lensing   Cluster and Anomalous X-Ray Flux Ratios of the Quadruply Imaged Quasar
  We present results from Chandra observations of SDSS J1004+4112, a strongly lensed quasar system with a maximum image separation of 15". All four bright images of the quasar, as well as resolved X-ray emission originating from the lensing cluster, are clearly detected. The emission from the lensing cluster extends out to approximately 1.5 arcmin. We measure the bolometric X-ray luminosity and temperature of the lensing cluster to be 4.7e44 erg s^-1 and 6.4 keV, consistent with the luminosity-temperature relation for distant clusters. The mass estimated from the X-ray observation shows excellent agreement with the mass derived from gravitational lensing. The X-ray flux ratios of the quasar images differ markedly from the optical flux ratios, and the combined X-ray spectrum of the images possesses an unusually strong Fe Kalpha emission line, both of which are indicative of microlensing. 
N. Ota, N. Inada, M. Oguri, K. Mitsuda, G. T. Richards, Y. Suto, W. N.   Brandt, F. J. Castander, R. Fujimoto, P. B. Hall, C...