Stellar velocity dispersion in narrow-line Seyfert 1 galaxies

Several authors have recently explored, for narrow-line Seyfert 1 galaxies (NLS1s), the relationship between black hole mass (M-BH) and stellar velocity dispersion (sigma(*)). Their results are more or less in agreement and seem to indicate that NLS1s fill the region below the fit obtained by Tremaine et al., showing a range of sigma(*) similar to that of Seyfert 1 galaxies, and a lower M-BH. Until now, the [O III] width has been used in place of the stellar velocity dispersion, but some indications have begun to arise against the effectiveness of the gaseous kinematics in representing the bulge potential, at least in NLS1s. Bian & Zhao have stressed the urgency of producing true sigma(*) measurements. Here, we present new stellar velocity dispersions obtained through direct measurements of the Ca II absorption triplet (similar to8550 Angstrom) in the nuclei of eight NLS1 galaxies. The resulting sigma(*) values and a comparison with [O III] confirm our suspicion that [O III] typically overestimates the stellar velocity dispersion. We demonstrate that NLS1s follow the M-BH-sigma(*) relation as Seyfert 1, quasars and non-active galaxies.