Related papers: Narrow-line Seyfert 1 Galaxies and the M_BH - sigm…
We present the results of a detailed multi-wavelength study of a sample of sixteen narrow-line Seyfert 1 (NLSy1) galaxies known in $\gamma$-rays so far. This includes a focused X-ray spectral analysis, to compare them with a more general…
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…
We present a detailed comparative systematic study using a sample of 221 Narrow-line Seyfert 1 (NLSy1) galaxies in comparison to a redshift matched sample of 154 Broad-line Seyfert 1 (BLSy1) galaxies based on their observations using ROSAT…
Radio-loud Narrow-line Seyfert 1 (NLS1) galaxies are unique probes of the formation of powerful radio jets at extreme (near-Eddington) accretion rates and low black hole masses, in a regime very different from classical blazars and,…
This paper presents a comparative study of emission line ratios of the Narrow Line Region (NLR) of Seyfert 1 and Seyfert 2 galaxies. It includes a literature compilation of the emission line fluxes [OII]3727A, [NeIII]3869A, [OIII]5007A and…
We create a baseline of the black hole (BH) mass (MBH) - stellar-velocity dispersion (sigma) relation for active galaxies, using a sample of 66 local (0.02<z<0.09) Seyfert-1 galaxies, selected from the Sloan Digital Sky Survey (SDSS).…
Spatially resolved emission-line spectroscopy is a powerful tool to determine the physical conditions in the narrow-line region (NLR) of active galactic nuclei (AGNs). We recently used optical long-slit spectroscopy to study the NLRs of a…
We present $J$-band near-infrared (NIR) imaging of the host galaxies of nine narrow-line Seyfert 1 galaxies (NLS1). Based on high-frequency radio observations at 37~GHz, seven of them could host powerful, most likely relativistic jets. Host…
Narrow-line Seyfert 1 galaxies, with their extreme properties, defy our current knowledge of active galactic nuclei and relativistic jet systems. They excite, and might help us answer, many questions concerning the evolution and unification…
We present a study of the host-galaxy morphologies of narrow- and broad-line Seyfert 1 galaxies (NLS1s and BLS1s) based on broad-band optical images from the Hubble Space Telescope archives. We find that large-scale stellar bars, starting…
Flat-spectrum radio-loud Narrow-Line Seyfert 1 galaxies (NLS1s) are a recently discovered class of $\gamma$-ray emitting Active Galactic Nuclei (AGN), that exhibit some blazar-like properties which are explained with the presence of a…
Narrow-line Seyfert 1 (NLS1) galaxies are a type of active galactic nuclei (AGN) that were originally classified as sources with little to no radio emission. Although the class is rather unified from an optical perspective, their radio…
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 present measurements of AGN type 1 luminosity function in the forbidden line [OIII]5007\AA using data from SDSS DR7. A special attention is paid to a subclass of Seyfert galaxies - the Narrow-Line Seyfert galaxies. These galaxies have…
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…
We present the first look at the spectral and timing analysis of Narrow-Line Seyfert 1 Galaxies (NLS1s) with the extended ROentgen Survey with an Imaging Telescope Array (eROSITA) on board the Spectrum-Roentgen-Gamma (SRG) mission. The…
We present a detailed study of 11 narrow-line Seyfert 1 galaxies (NLS1s) from the Six-degree Field Galaxy Survey (6dFGS) that both have optical and X-ray spectroscopic observations. There are five complex NLS1s (C-NLS1s) and six simple…
Narrow-line Seyfert 1 galaxies (NLS1s) is one of the few classes of active galactic nuclei (AGN) harboring powerful relativistic jets and detected in $\gamma$ rays. NLS1s are well-known X-ray sources. While in non-jetted sources the origin…
Line profiles can provide fundamental information on the physics of active galactic nuclei (AGN). In the case of narrow-line Seyfert 1 galaxies (NLS1s) this is of particular importance since past studies revealed how their permitted line…
We present the first systematic study of (non-radio-selected) radio-loud narrow-line Seyfert 1 (NLS1) galaxies. Cross-correlation of the `Catalogue of Quasars and Active Nuclei' with several radio and optical catalogues led to the…