An X-ray spectral study of 24 type 1 active galactic nuclei

I present a study of the X-ray spectral properties of a sample containing 24type-1 active galactic nuclei using the medium spectral resolution of ``ASCA''.The sample consists of 20 radio-quiet objects and 4 radio-loud objects. Asimple power-law continuum absorbed by Galactic material provides a very poordescription of the spectra of most objects. Deviations from the power-law formare interpreted in terms of X-ray reprocessing/absorption processes. Inparticular, at least half of the objects show K-shell absorption edges of warmoxygen (O vii and O viii) characteristic of optically-thin, photoionizedmaterial along the line-of-sight to the central engine, the so-called warmabsorber. It is found that objects with significant optical reddening displaydeep O vii edges. Coupled with other evidence, this suggests the existence ofdusty warm plasma. A radiatively driven outflow originating from the moleculartorus is probably the source of this plasma. Rapid variability of the warmabsorber also points to there being another component closer to the centralsource and probably situated within the broad line region. Spectral features at energies characteristic of cold fluorescent ironK$\alpha$ emission are common. Radio-quiet objects have iron emission welldescribed as originating from either the inner regions of an accretion disk or,in a small number of cases, from the molecular torus. Two of the radio-loudobjects (3C~120 and 3C~382) have a much broader feature which presents problemsfor the relativistic disk model. The presence of radio-jets may be important informing this spectral feature.Comment: 27 pages, 9 figures. Accepted for publication in MNRA