Abstract
We utilize the diagnostic power of the [SII] lambdalambda 6716, 6731 intensity ratio to measure the density of the narrow-line region (NLR) systematically for a large sample of narrow-line Seyfert 1 (NLS1) galaxies, and we perform a comparison with a sample of broad-line Seyfert 1 (BLS1) galaxies. The key detection is the discovery of a 'zone of avoidance' in density in the sense that AGN with broad lines (FWHM(Hbeta) > 2000 km s(-1) ) avoid low densities, while NLS1 galaxies show a wider distribution in the NLR density, including a significant number of objects with low densities. A correlation analysis further shows that the Eddington ratio L/L[Edd] anticorrelates with density. We tentatively favor the effects of winds/outflows, stronger in NLS1 galaxies than in BLS1 galaxies, to explain the observed trends.
