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X. Dai, G. Chartas, G. P. Garmire (Penn State Univ.)
We present preliminary results from a Chandra study of High Redshift Quasars (z>2) with the aid of lensing. Most studies of high redshift quasars to date are based on either summing the individual spectra of many faint X-ray sources or deep observations of a few quasars. Gravitational lensing can provide a flux magnification from a few to ~100. The extra magnification of lensed quasars enables us to obtain high signal-to-noise spectra of distant quasars with less observing time and allows us to search for changes in quasar properties, such as the accretion process over four orders of magnitude in intrinsic X-ray luminosity. A sample of 12 gravitationally lensed high redshift quasars (8 radio quiet and 4 radio loud) has been observed with ACIS onboard Chandra. We present our first results of our analysis on the evolution of photon indices and \alphaox with redshift and the dependence of these quasar properties with luminosity.
We acknowledge the financial support by NASA grant NAS 8-01128.
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Bulletin of the American Astronomical Society,
© 2003. The American Astronomical Soceity.