Narrow-line Seyfert 1 galaxies: a search for defining parameters

Luigi Gallo, Saint Mary's University

Narrow-line Seyfert 1 galaxies (NLS1s) are thought to represent an early stage of Seyfert 1 (S1) evolution. In all energy bands, NLS1s tend to exhibit characteristics that are unlike typical S1s. They possess some of the most intriguing X-ray properties and the most extreme variability seen in radio-quiet AGN. From epoch-to-epoch the spectral variations can be so significant that fitting data with self-consistent models becomes challenging. We will present multi-epoch observations of several NLS1s and discuss potentially self-consistent models to describe the X-ray spectra, and the changes. Moreover we will consider these results in combination with multi-wavelength data to examine the factors driving the differences between S1s and NLS1s.