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S. Vaughan (Leicester Univ.), R. Edelson (Leicester Univ., UCLA), J. Reeves, R. Warwick (Leicester Univ.)
We present a systematic analysis of the X-ray spectral properties of all 22 "narrow-line" (H-beta FWHM < 2000 km/s) Seyfert 1 galaxies with public ASCA data as of the end of 1998. The 0.6-2 keV power-law spectral slopes span a rather wide range (Gamma = 1.6 to 2.6), but the mean is Gamma = 2.1, which is only slightly steeper than that of "normal" Seyfert 1s. All but four spectra require a soft excess component, which can contain the bulk of the luminosity, even in the relatively hard ASCA band.
Many of these spectra show further significant spectral complexity. Most notably, six of these 22 objects show evidence for a broad absorption feature centred in the energy range 1.1-1.4 keV, possibly due to resonance absorption in highly ionized material. A further three sources exhibit "warm absorption" edges in the 0.7-0.9 keV bandpass. Remarkably, all of the nine "absorbed" sources have H-beta line widths below 1000 km/s, which is less than the median value for the sample. This tendency for very narrow line widths to correlate with the presence of ionized absorption features may provide a further clue in the puzzle of active galactic nuclei.
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