Related papers: Active Galactic Nuclei Emission-Line Properties Ve…

We present new Chandra X-ray observations of seven low-mass black holes (~1e6 Msun) accreting at low Eddington ratios between -2.0<log L/Ledd<-1.5. We compare the X-ray properties of these seven low-mass active galactic nuclei (AGN) to a…

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…

The recent discovery by Fermi/LAT of high-energy (E>100 MeV) gamma rays from Narrow-Line Seyfert 1 Galaxies (NLS1s) made evident the existence of a third class of gamma-ray emitting Active Galactic Nuclei (AGN), after blazars and radio…

We use the narrow [Ne v] $\lambda$3427 emission line detected in the recently published JWST spectra of two galaxies, at z = 6.9 and 5.6, to study the key properties of the active galactic nuclei (AGN) and the supermassive black holes…

We study the UV spectra of narrow-line Seyfert~1 (NLSy1) galaxies and compare them with ``normal'' AGN. Similar to their optical lines, the NLSy1s show narrower UV lines. They are also characterized by weaker CIV 1549, CIII] 1909, and…

Using the BH masses deduced from the empirical relation of Kaspi et al. (2000) and assuming that the optical luminosity is provided by the accretion disc, we show that Narrow Line Seyfert Galaxies 1 (NLS1s) accrete at super-Eddington rates,…

From a parent catalog of 561 changing-look active galactic nuclei (CL-AGNs) identified by Guo et al. (2025), we investigate the evolutionary sequence of broad emission lines using a redshift-selected subset (0.35 < z < 0.45) of 54 CL-AGNs…

We examine the near-infrared (NIR) emission from low-luminosity AGNs (LLAGNs). Our galaxy sample includes 15 objects with detected 2-10 keV X-ray emission, dynamical black hole mass estimates from the literature, and available Gemini/NIFS…

We analyzed a sample of $\sim$113,000 galaxies ($\rm z < 0.3$) from the Sloan Digital Sky Survey, divided into star-forming, composite, Seyfert, and LINER types, to explore the relationships between UV-to-optical colors ($\rm u-r$), star…

Recent James Webb Space Telescope (JWST) observations have revealed a population of compact extragalactic objects at $z\gtrsim4$ with red near-infrared colors, which have been dubbed as ``Little Red Dots" (LRDs). The…

We have investigated the ensemble regularities of the equivalent widths (EWs) of MgII 2800 emission line of active galactic nuclei (AGNs), using a uniformly selected sample of 2092 Seyfert 1 galaxies and quasars at 0.45 <= z <= 0.8 in the…

We measure oxygen and nitrogen abundances for 14 star-forming emission line galaxies (ELGs) at 0.11<z<0.5 using Keck/LRIS optical spectroscopy. The targets exhibit a range of metallicities from slightly metal-poor like the LMC to…

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 present a spectroscopic search for broad H$\alpha$ emitters at z$\approx$3.7-6.5 in the GOODS-N field, utilizing JWST/NIRCam slitless spectroscopy from FRESCO and CONGRESS, complemented by JADES imaging. We identify 19 broad H$\alpha$…

Narrow-line Seyfert 1 galaxies (NLS1s) exhibit extreme soft X-ray excess and large variability. We argue that both features can be basically accounted for by the slim disk model. We assume that a central black-hole mass in NLS1 is…

We present black hole masses and accretion rates for 182 Type 1 AGN in COSMOS. We estimate masses using the scaling relations for the broad Hb, MgII, and CIV emission lines in the redshift ranges 0.16<z<0.88, 1<z<2.4, and 2.7<z<4.9. We…

We used a large, homogeneous sample of 4178 z <= 0.8 Seyfert 1 galaxies and QSOs selected from the Sloan Digital Sky Survey to investigate the strength of Fe II emission and its correlation with other emission lines and physical parameters…

We investigate the Eddington ratio distribution of X-ray selected broad-line active galactic nuclei (AGN) in the redshift range 1.0<z<2.2, where the number density of AGNs peaks. Combining the optical and Subaru/FMOS near-infrared…

Narrow line Seyfert 1 galaxies (NLS1s) are believed to be powered by accretion of matter onto low mass black holes (BHs) in spiral host galaxies with BH masses M_BH of 10^6 - 10^8 M_sun . However, the broad band spectral energy distribution…

Although the properties of the narrow-line region (NLR) of active galactic nuclei(AGN) have been deeply studied by many authors in the past three decades, many questions are still open. The main goal of this work is to explore the NLR of…