Related papers: Narrow-line Seyfert 1 Galaxies and the M_BH - sigm…
It is not yet well known whether narrow line Seyfert 1 (NLS1) galaxies follow the $M_{BH} - \sigma_{\star}$ relation found for normal galaxies. Emission lines, such as [SII] or [OIII]$\lambda$5007, have been used as a surrogate of the…
We have studied the physical properties of a sample of narrow-line Seyfert 1 (NLS1) galaxies, and present a summary of our previous results, and new results. In particular, we have previously shown that (1) the locus of NLS1 galaxies on the…
Several authors recently explored the Black-Hole mass (M_BH) vs. stellar velocity dispersion (sigma_*) relationship for Narrow Line Seyfert 1 galaxies (NLS1s). Their results are more or less in agreement and seem to indicate that NLS1s fill…
Narrow line Seyfert 1 (NLSy1) galaxies constitute a class of active galactic nuclei characterized by the full width at half maximum (FWHM) of the H$\beta$ broad emission line < 2000 km/s and the flux ratio of [O III] to H$\beta$ < 3. Their…
We have studied the properties of Seyfert galaxies with high [OIII]5007 blueshifts (`blue outliers'), originally identified because of their strong deviation from the M_BH - sigma relation of normal, narrow-line Seyfert 1 (NLS1) and…
We have compiled a list of 83 objects classified as Narrow-Line Seyfert 1 galaxies (NLS1s) or known to have a broad Balmer component narrower than 2000 km/s. Out of these, 19 turned out to have been spectroscopically misidentified in…
Narrow-line Seyfert 1 galaxies (NLS1s) are arguably one of the key AGN subclasses in investigating the origin of the black hole mass - stellar velocity dispersion (M-sigma) relation because of their high accretion rate and significantly low…
We re-examine the locus of narrow line Seyfert 1 galaxies on the M_BH--sigma (black hole mass--bulge velocity dispersion) plane in the light of the results from large new optically selected samples. We find that (1) soft X-ray selected…
This work studies the optical emission line properties and physical conditions of the narrow line region (NLR) of seven narrow-line Seyfert 1 galaxies (NLS1). Our results show that the flux carried out by the narrow component of H-beta is,…
We report here our comparative analysis of active galactic nucleus (AGN) and star formation (SF) characteristics of a sample of narrow-line Seyfert 1 (NLS1) and broad-line Seyfert 1 (BLS1) galaxies. Our sample consisted of 373 BLS1 and 240…
We present a statistical study of a large, homogeneously analyzed sample of narrow-line Seyfert 1 (NLS1) galaxies, accompanied by a comparison sample of broad-line Seyfert 1 (BLS1) galaxies. Optical emission-line and continuum properties…
We present optical spectra and emission-line ratios of 12 Narrow-Line Seyfert 1 (NLS1) galaxies that we observed to study the ionizing EUV continuum. A common feature in the EUV continuum of active galactic nuclei is the big blue bump…
We 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…
It is known that the spectral energy distribution (SED) of the nuclear radiation of narrow-line Seyfert 1 galaxies (NLS1s) has different shapes with respect to that of ordinary broad-line Seyfert 1 galaxies (BLS1s), particularly in…
Controversy regarding whether Narrow Line Seyfert 1 galaxies (NLS1s) follow the same black hole --- galactic bulge relation as normal galaxies has been raised by Mathur et al. (2001) and Ferrarese et al. (2001). In this paper, the…
Narrow Line Seyfert 1 galaxies represent a distinct category in the larger family of Type 1 Active Galactic Nuclei. The occurrence of emission line profiles not broader than 2000 km/s, combined with luminosity estimates comparable to those…
The properties of narrow-line Seyfert 1 (NLS1) galaxies, the links and correlations between them, and the physics behind them, are still not well understood. Apart from accretion rates and black hole masses, density and outflows were…
We investigate gas metallicity of narrow-line regions in narrow-line Seyfert 1 galaxies (NLS1s) and broad-line ones (BLS1s) in order to examine whether or not there is a difference in the gas metallicity between the two populations of…
In order to study the slope and strength of the non-stellar continuum, we analyzed a sample of nearby Narrow Line Seyfert 1 (NLS1). Also, we re-examined the location of NLS1 galaxies on the M $-$ $\sigma$ relation using the stellar velocity…
Narrow-line Seyfert 1 galaxies (NLS1s) are active galactic nuclei (AGN) recently identified as a new class of $\gamma$-ray sources. The high energy emission is explained by the presence of a relativistic jet observed at small angles, just…