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G. Risaliti, M. Elvis (Harvard-Smithsonian Center for Astrophysics), A. Marconi, M. Salvati (Arcetri Observatory, ITALY)
We present Chandra observations of 18 spectroscopically selected broad line quasars, already known to be soft X-ray weak from previous ROSAT observations. All the sources but one are detected by Chandra. Most objects are underluminous by a factor from 5 to >100 in the 2-10 keV band. The spectral analysis suggests that this low observed emission is mostly due to intrinsic weakness, while absorption can only play a minor role. We discuss the possibility that this population of quasars, intrinsically different from the ``normal'' one, is a significant contributor to the X-ray background.
This is partially supported by NASA Contract NAS8-39073 and NASA Grant GO2-3142X
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Bulletin of the American Astronomical Society,
© 2003. The American Astronomical Soceity.