Cracco, V.V.CraccoCiroi, S.S.CiroiBerton, M.M.BertonDi Mille, F.F.Di MilleFOSCHINI, LUIGILUIGIFOSCHINILa Mura, G.G.La MuraRafanelli, P.P.Rafanelli2020-04-302020-04-3020160035-8711http://hdl.handle.net/20.500.12386/24387We revisited the spectroscopic characteristics of narrow-line Seyfert 1 galaxies (NLS1s) by analysing a homogeneous sample of 296 NLS1s at redshift between 0.028 and 0.345, extracted from the Sloan Digital Sky Survey (SDSS-DR7) public archive. We confirm that NLS1s are mostly characterized by Balmer lines with Lorentzian profiles, lower black hole masses and higher Eddington ratios than classic broad-line Seyfert 1 (BLS1s), but they also appear to be active galactic nuclei (AGNs) contiguous with BLS1s and sharing with them common properties. Strong Fe II emission does not seem to be a distinctive property of NLS1s, as low values of Fe II/Hβ are equally observed in these AGNs. Our data indicate that Fe II and Ca II kinematics are consistent with the one of Hβ. On the contrary, O I λ8446 seems to be systematically narrower and it is likely emitted by gas of the broad-line region more distant from the ionizing source and showing different physical properties. Finally, almost all NLS1s of our sample show radial motions of the narrow-line region highly ionized gas. The mechanism responsible for this effect is not yet clear, but there are hints that very fast outflows require high continuum luminosities (>10<SUP>44</SUP> erg s<SUP>-1</SUP>) or high Eddington ratios (log (L<SUB>bol</SUB>/L<SUB>Edd</SUB>) > -0.1).STAMPAenArticle10.1093/mnras/stw16892-s2.0-84988892507000384674100008https://academic.oup.com/mnras/article/462/2/1256/2589433https://arxiv.org/abs/1607.034382016MNRAS.462.1256CFIS/05 - ASTRONOMIA E ASTROFISICAScienze Fisiche Settori ERC (ERC) di riferimento::PE9 Universe sciences: astro-physics/chemistry/biology; solar systems; stellar, galactic and extragalactic astronomy, planetary systems, cosmology, space science, instrumentation