出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：We present early results from an analysis of variability in the optical–to–X-ray spectral index, aOX, in sample of 97 Seyfert 1–1.2 AGN. Simultaneous SEDs from XMM-Newton (PN and Optical Monitor instruments) are used to determine aOX and related SED parameters, using accretion disc model fits and accounting for intrinsic dust extinction. Our work supports the idea that the greater variability in aOX seen in Narrow-Line Seyfert 1 AGN (NLS1s) is driven primarily by changes in the corona, not the accretion disc. We confirm that NLS1s are accreting at high Eddington ratios, and also find higher peak temperatures in their accretion discs. We discuss the desirability of being able to constrain the inner radius of the accretion disc in a large sample of Broad- and Narrow-line Seyfert 1s, but this is currently difficult to do in large samples with the data available.
