Related papers: The Fe II problem in NLS1s
No. Due to their apparently extreme optical to X-ray properties, Narrow Line Seyfert 1s (NLSy1s) have been considered a special class of active galactic nuclei (AGN). Here, we summarize observational results from different groups to…
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…
Accretion and ejection of matter in active galactic nuclei (AGN) are tightly connected phenomena and represent fundamental mechanisms regulating the growth of the central supermassive black hole and the evolution of the host galaxy.…
A study of [Fe II] lines at various positions within the H II regions M42 and M43 is presented. The relative intensities of selected optical [Fe II] lines are shown to be correlated with the intensity of the apparent nebular continuous…
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 on AGN with extremely soft X-ray spectra observed with ROSAT. From their optical emission lines these objects are classified as narrow-line Seyfert 1 galaxies (NLS1), almost all with extremely large Fe II/H-beta ratios and…
We systematically analyzed the high-quality Suzaku data of 88 Seyfert galaxies. We obtained a clear relation between the absorption column density and the equivalent width of the 6.4 keV line above 10$^{23}$ cm$^{-2}$, suggesting a…
The enrichment of Fe, relative to alpha-elements such as O and Mg, represents a potential means to determine the age of quasars and probe the galaxy formation epoch. To explore how \ion{Fe}{2} emission in quasars is linked to physical…
We report near-infrared spectroscopic data for the Seyfert 2 galaxy Mrk 78, taken with the LIRIS near-infrared camera/spectrometer at the William Herschel Telescope (WHT). The long-slit spectra clearly show extended emission. The resolution…
A sample of 22 narrow-line Seyfert 1 (NLS1) and 47 broad-line Seyfert 1 (BLS1) galaxies observed with Suzaku is used to examine the Fe K band properties of each group. Three different models are used to examine the presence of: narrow…
We present the kinematical properties of the UV and optical \FeII\ emission gas based on the velocity shift and line width measurements of a sample of 223 Type 1 active galactic nuclei (AGNs) at 0.4 $<$ z $<$ 0.8. We find a strong…
We present J-band long-slit spectroscopic observation of NGC 1068 classified as a Seyfert 2 galaxy. J-band observations with OAO/ISLE provide clear detection of spatially extended [Fe II]1.257um and [P II]1.188um lines. We found that [Fe…
The latest observations of line and continuum spectra emitted from the extended narrow line region (ENLR) of the Seyfert 2 galaxy NGC 7212 are analysed using models accounting for photoionization from the active nucleus and shocks. The…
NLTE line formation calculations of FeI in the solar atmosphere are extended to include weak optical lines. Previously established atomic models are used to discriminate between different ways of treating collisional interaction processes.…
Soft X-ray spectroscopy of Seyfert 2 galaxies offers perhaps the best method to probe the possible connection between AGN activity and star formation. Obscuration of powerful radiation from the inferred nucleus allows for detailed study of…
Current emission-line based estimates of the metallicity of active galactic nuclei (AGN) at both high and low redshifts indicate that AGN have predominantly solar to supersolar metallicities. This leads to the question: do low metallicity…
It was suggested that the prominent feature of the optical Fe II emission has a connection with the accretion process in active galactic nuclei (AGN). For a large sample of 4037 quasars ($z < 0.8$) with measured $\rm H\beta$ line dispersion…
We present near and mid--IR observations of a sample of Seyfert II galaxies drawn from the $12\mu$m Galaxy Sample. The sample was observed in the J, H, K, L, M and N bands. Galaxy Surface Brightness Profiles are modeled using nuclear,…
Thirty years ago the optical counterpart of the x-ray source 1H0707-495 was discovered to be a 15th magnitude broad-line Seyfert galaxy with a rich Fe II emission line spectrum typical of the AGN subclass sometimes referred to as the I Zw 1…
Non-local thermodynamic equilibrium (NLTE) line formation for neutral and singly-ionized iron is considered through a range of stellar parameters characteristic of cool stars. A comprehensive model atom for Fe I and Fe II is presented. Our…