Related papers: The link between X-ray complexity and optical line…
We have explored the relationship between the [O III] $\lambda$5007 and the 2--10 keV luminosities for a sample of Broad- and Narrow-Line Seyfert 1 galaxies (BLSy1 and NLSy1, respectively). We find that both types of Seyferts span the same…
Narrow Line Seyfert 1 (NLSy1) galaxies have recently received a lot of attention due to their unusual optical--X-ray properties which are not yet well understood. Photoionization models of the circum-nuclear emission/absorption regions…
We examine the accretion properties in a sample of 42 hard (3-60keV) X-ray selected nearby broad-line AGNs. The energy range in the sample is harder than that usually used in the similar previous studies. These AGNs are mainly complied from…
In this contribution we report on the study of the optical emission lines and X-ray spectra of a sample of Type 1 AGNs, collected at the Sloan Digital Sky Survey database and observed by the XMM Newton satellite. Exploiting the different…
We present a new accurate catalog of narrow-line Seyfert 1 galaxies (NLS1s) in the southern hemisphere from the Six-degree Field Galaxy Survey (6dFGS) final data release, which is currently the most extensive spectroscopic survey available…
It is well-known that the higher policyclic aromatic hydrocarbon (PAH) abundance, lower black hole mass, higher accretion rate and lower luminosities are among the major characteristics of Narrow-Line Seyfert galaxies (NLS1), when they are…
We argue that both the extreme soft X-ray excess and the large-amplitude variability of Narrow-Line Seyfert 1 galaxies (NLS1s) can be explained in the framework of the slim disk model. When the disk luminosity approaches the Eddington…
Active Galactic Nuclei (AGN) are axisymmetric systems to first order; their observed properties are likely strong functions of inclination with respect to our line of sight. However, except for a few special cases, the specific inclinations…
We present modeling and interpretation of the continuum and emission lines for a sample of 51 unobscured Type 1 active galactic nuclei (AGN). All of these AGNs have high quality spectra from both XMM-Newton and Sloan Digital Sky Survey…
We present spectroscopic observations of 27 active galactic nuclei (AGN) with some of the lowest black hole (BH) masses known. We use the high spectral resolution and small aperture of our Keck data, taken with the Echellette Spectrograph…
Black hole mass determination in active galaxies is a key issue in understanding various luminosity states. In the present paper we try to generalise the mass determination method based on the X-ray excess variance, successfully used for…
Narrow-line Seyfert 1 (NLS1) galaxies are active galactic nuclei (AGN) believed to be in the early stages of their evolution. A fraction of them have been found to host relativistic jets. Due to the lack of large-scale diffuse radio…
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…
Narrow-Line Seyfert 1 galaxies (NLS1s) are generally believed to be radio-quiet Active Galactic Nuclei (AGN) with relatively less-massive (10$^{5}$$-$10$^{8}$~M$_{\odot}$) Super-Massive Black Holes (SMBH). Using the FIRST radio detections…
We present a new accurate sample of narrow-line Seyfert 1 galaxies (NLS1s) in the southern hemisphere from the Six-degree Field Galaxy Survey (6dFGS). Based on the optical spectral features, 167 sources were classified as NLS1s. We derived…
I review observational data on X-ray energy spectra and variability of Seyfert 1 and Narrow Line Seyfert 1 galaxies, and compare them to black hole binary (BHB) systems. There seems to be greater similarity of time averaged properties (i.e.…
We present HST/ACS observations of ten galaxies that host narrow-line Seyfert 1 (NLS1) nuclei, believed to contain relatively smaller mass black holes accreting at high Eddington ratios. We deconvolve each ACS image into a nuclear point…
A sample of narrow-line (NLS1) and broad-line Seyfert 1 (BLS1) galaxies observed with Suzaku is presented. The final sample consists of 22 NLS1s and 47 BLS1s, for a total of 69 AGN that are all at low redshift (z<0.5) and exhibit low host…
We estimated the spin values of the supermassive black holes (SMBHs) of the active galactic nuclei (AGN) for a large set of Narrow Line Seyfert 1 (NLS1) galaxies assuming the inclination angle between the line of sight and the axis of the…
We propose two statistical tests to investigate how we see the nuclear region (r < 0.1 pc) of Narrow-Line Seyfert 1 galaxies (NLS1s). 1) The high-ionization nuclear emission-line region (HINER) test: Seyfert 1 galaxies (S1s) have…