A COMPARISON OF THE HARD ASCA SPECTRAL SLOPES OF BROAD-LINE AND NARROW-LINE SEYFERT-1 GALAXIES

The soft (approximate to 0.1-2.0 keV) X-ray spectra of narrow-line Sey fert 1 galaxies are known to be generally steeper than those of Seyfer t 1 galaxies with broader optical permitted lines. This has been attri buted to the presence of strong soft X-ray excesses, over the hard X-r ay power law, in many narrow-line Seyfert 1s. Here we use the currentl y available ASCA data to systematically compare the harder (approximat e to 2-10 keV) X-ray continua of soft ROSAT narrow-line Seyfert 1s wit h those of Seyfert 1s with larger HP FWHM. Our robust and non-parametr ic testing suggests, with high statistical significance, that soft ROS AT narrow-line Seyfert 1s have generally steeper intrinsic hard X-ray continua than Seyfert 1s with larger HP FWHM. The hard photon index tr end appears similar to the previously known soft photon index trend, a lthough with a reduced photon index spread. If the soft X-ray excesses of all Seyfert 1s are confined to below approximate to 1 keV they can not directly affect the approximate to 2-10 keV spectra studied here. However, as suggested for the extreme narrow-line Seyfert 1 RE J 1034 + 393, a strong soft X-ray excess may affect the accretion disc corona which creates the underlying hard X-ray power law. If this is occurri ng, then more detailed study of this physical process could give clues about the formation of the underlying continua of all Seyferts. Other effects, such as intrinsic 2-10 keV continuum curvature, could also l ead to the observed photon index trend and need further study.