New insights into AGNs with low-mass black holes and high accretion rates: the case of narrow-line Seyfert 1 galaxies

Narrow-line Seyfert 1 (NLS1) galaxies are believed to harbor low-mass black holes accreting at high rates, and they are therefore important targets when studying the nature of black hole growth, galaxy evolution, and accretion physics. We have rigorously studied the physical properties of a sample of NLS1 galaxies. We briefly review previous findings and present new results, including: (1) The locus of NLS1 galaxies on the M _BH-σ plane, which we find to follow the relation of non-active galaxies after removing objects obviously dominated by outflows. (2) The presence of “blue outliers” which hint at extreme outflows as they would be predicted from merger models. (3) More subtle evidence for winds and outflows across the whole NLS1 population. (4) New correlations and trends which link black hole mass, Eddington ratio and physical parameters of the emission-line region. A new element is added to the eigenvector 1 space based on a principal component analysis, which aims at identifying the main drivers of AGN correlation properties.