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J. Kuraszkiewicz (SAO \& NCAC-Warsaw, Poland), B.J. Wilkes (SAO), B. Czerny (NCAC-Warsaw, Poland), S. Mathur (SAO)
We compare the UV spectra of narrow-line Seyfert 1 (NLSy1) galaxies with the ``normal'' broad line AGN and show that the NLSy1s are characterized by narrower UV lines, weaker CIV\lambda1549, CIII]\lambda1909 emission and stronger SiIV+OIV]\lambda1400, SiIII]\lambda1892, AlIII\lambda1857 emission. We show that such spectra are the result of BLR cloud densities that are larger than normal by factors 10-100, and with a lower ionization parameter. This is due to the steep soft X-ray spectra (which characterize the NLSy1 SEDs) which change the conditions in the two phase cloud-intercloud medium, resulting in higher BLR cloud densities and larger BLR radii. We also show that the steep soft and hard X-ray indices, observed in NLSy1s, can be explained by an accretion disk and corona model with large L/LEdd ratios.
These UV properties add to the optical and X-ray properties known to be part of the Boroson & Green eigenvector 1. We propose that the L/LEdd is the physical parameter driving this eigenvector.