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Session 23 - High Luminosity AGN and QSOs.
Oral session, Monday, June 10
Union Theater,

[23.04] The 3--53 keV spectrum of the quasar 1508+5714: X-rays from z = 4.3

E. C. Moran (IGPP/LLNL), D. J. Helfand (Columbia U.)

Three of 20 radio-selected X-ray sources from our reanalysis of the Einstein\/ IPC database proved to be quasars with redshifts in excess of 3. The most distant example, 1508+5714 at z = 4.30, is presently the most luminous and highest flux X-ray quasar known with z > 3.4. We have obtained the X-ray spectrum of 1508+5714 with the ASCA\/ Observatory in the 0.5--10 keV band, which corresponds to the 3--53 keV range in the quasar rest frame.

The X-ray properties of quasars are potentially sensitive indicators of their evolution, but to date fewer than 25 high-redshift (z > 3) X-ray quasars have been detected at X-ray wavelengths. Thus, each new example represents a valuable resource for quasar evolution studies. We describe the spectral properties of 1508+5714 in this context, and our current efforts to identify more of these rare objects.

Program listing for Monday