In this work we address the still open question of the nature of narrow-line Seyfert 1 galaxies (NLS1s): are they really active nuclei with lower mass black holes (BHs) than Seyfert 1 galaxies (S1s) and quasars? Our approach is based on the recently discovered physical connections between nuclear supermassive BHs and their hosting spheroids (spiral bulges or elliptical galaxies). In particular, we compare BH masses of NLS1s and S1s, analyzing the properties of their hosts by means of spectroscopic and photometric data in the optical wavelength domain. We find that NLS1s fill the low BH mass and bulge luminosity values of the MBH-MB relation, a result strongly suggesting that NLS1s are active nuclei in which less massive BHs are hosted by less massive bulges. The correlation is good, with a relatively small scatter fitting simultaneously NLS1s, S1s, and quasars. On the other hand, NLS1s seem to share the same stellar velocity dispersion range as S1s in the MBH-σ* relation, indicating that NLS1s have a smaller BH/bulge mass ratio than S1s. These two conflicting results support in any case the idea that NLS1s could be young S1s. Finally, we do not confirm the significantly nonlinear BH-bulge relation claimed by some authors. Partially based on observations made with the Asiago 1.82 m telescope of the Padova Astronomical Observatory

Several authors have recently explored, for narrow-line Seyfert 1 galaxies (NLS1s), the relationship between black hole mass (MBH) and stellar velocity dispersion (σ*). 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 σ* similar to that of Seyfert 1 galaxies, and a lower MBH. Until now, the [OIII] 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 σ* measurements. Here, we present new stellar velocity dispersions obtained through direct measurements of the CaII absorption triplet (~8550 Å) in the nuclei of eight NLS1 galaxies. The resulting σ* values and a comparison with σ[OIII] confirm our suspicion that [OIII] typically overestimates the stellar velocity dispersion. We demonstrate that NLS1s follow the MBH-σ* relation as Seyfert 1, quasars and non-active galaxies

We present new important results about the intermediate-type Seyfert galaxy Mrk 315, recently observed through optical imaging and integral-field spectroscopy. Broad-band images were used to study the morphology of the host galaxy, narrow-band Hα images to trace the star-forming regions, and middle-band [OIII] images to evidence the distribution of the highly ionized gas. Some extended emission regions were isolated and their physical properties studied by means of flux-calibrated spectra. High-resolution spectroscopy was used to separate different kinematic components in the velocity fields of gas and stars. Some peculiar features characterize this apparently undisturbed and moderately isolated active galaxy. Such features, already investigated by other authors, are re-analysed and discussed in the light of these new observations. The most relevant results we obtained are: the multitiers structure of the disc; the presence of a quasi-ring of regions with star formation much higher than previous claims; a secondary nucleus confirmed by a stellar component kinematically decoupled by the main galaxy; a new hypothesis about the controversial nature of the long filament, initially described as hook shaped, and more likely made of two independent filaments caused by interaction events between the main galaxy and two dwarf companions

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Abstract. Measuring stellar velocity dispersion (σ) in Narrow-Line Seyfert 1 (NLS1) with optical spectra, can be very difficult because of the large and bright Fe II multiplets, which completely suppress the typically used stellar absorption lines. Indeed, σ values are to date available only for 2 NLS1s. Here we present new σ measurements of three NLS1s observed in the spectral range centered around the Ca II triplet (λ ∼ 8600Å). Moreover, we compare σ with the gaseous velocity dispersion finding that the σ=FWHM([O III]5007Å)/2.35 relation (Nelson & Whittle 1995) is not satisfied by our galaxies.

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Abstract. During the last decades many authors have concentrated their efforts on understanding what are the most efficient mechanisms to feed an AGN. Several solutions have been proposed, as the presence of circumnuclear star clusters, nuclear bars/disks/spirals, and the interaction between galaxies, in form of close encounters and mergers. Here we present new results about an isolated, intermediate-type Seyfert galaxy, Mrk315. The analysis of broad-and narrow-band images, and integral field spectra revealed a spiral-like structure hidden under the E/S0 morphology of the galaxy, and confirmed the presence of a nuclear jet-like feature, forming a sort of very extended "hook". Moreover, our data confirmed the supposed nature of the already known knot, located at 2" from the active nucleus, as a secondary nucleus, residual of a minor merger bewteen the galaxy and a small nucleated companion.

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