Related papers: Narrow-Line Seyfert 1 Galaxies
We present oxygen abundances relative to hydrogen (O/H) in the narrow line regions (NLRs) gas phases of Seyferts 1 (Sy 1s) and Seyferts 2 (Sy 2s) Active Galactic Nuclei (AGNs). We used fluxes of the optical narrow emission line intensities…
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…
Radio-Loud narrow-line Seyfert 1 galaxies (NLS1s), especially the extremely radio-loud ones, are widely accepted as the jetted versions of NLS1s. We explore the radio-loud fraction for NLS1s with recently released LoTSS DR1 at 150 MHz. The…
We present the broad-band soft and hard X-ray spectral analysis of 8 Narrow Line Seyfert 1 galaxies extracted from the IBISCO Sample. The study also focuses on the properties of the NLS1 in our sample in relation to those of the IBISCO…
We describe how recent X-ray surveys have led to advances in the understanding of ultrasoft narrow-line Seyfert 1 galaxies. The number of known ultrasoft narrow-line Seyfert 1s has increased greatly in recent years due to X-ray surveys, and…
The discovery by the Large Area Telescope on board Fermi of variable gamma-ray emission from radio-loud narrow-line Seyfert 1 (NLSy1) galaxies revealed the presence of a possible third class of Active Galactic Nuclei (AGN) with relativistic…
The term 'active galactic nuclei' (AGN) subtends a huge variety of objects, classified on their properties at different wavelengths. Peaked sources (PS) represent a class of AGN at the first stage of evolution, characterised by a peaked…
We present the results of new radio observations carried out with the Karl G. Jansky Very Large Array C-configuration at 5.5 GHz for a sample of southern narrow-line Seyfert 1 galaxies (NLS1s). This work increases the number of known…
The detection by Fermi-LAT of gamma-ray emission from radio-loud Narrow-Line Seyfert 1s (NLS1s) indicates that relativistic jets do not form only in blazars and radio galaxies, but also in other AGN populations. Despite a spectral energy…
We report on the identification of a new $\gamma$-ray-emitting narrow-line Seyfert 1 (NLS1) galaxy, SDSS J122222.55+041315.7, which increases the number of known objects of this remarkable but rare type of active galactic nuclei (AGN) to…
The detection of gamma rays from a small number of Narrow Line Seyfert 1 galaxies by the LAT instrument onboard Fermi seriously challenged our understanding of AGN physics. Among the most important findings associated with their discovery…
Narrow-Line Seyfert 1 galaxies have been established as a new class of gamma-ray emitting AGN with relatively low black hole masses, but near-Eddington accretion rates. Other extragalactic gamma-ray sources observed so far such as Flat…
The host galaxy conditions for rapid supermassive black hole growth are poorly understood. Narrow-line Seyfert 1 (NLS1) galaxies often exhibit high accretion rates and are hypothesized to be prototypes of active galactic nuclei (AGN) at an…
We present the main results of broad band (0.1-10 keV) BeppoSAX observations of a selected sample of Narrow Line Seyfert 1 galaxies (NLS1s). We have performed a spectroscopic analysis of LECS and MECS data to test their average spectral…
Narrow-line Seyfert 1 (NLS1) galaxies are a peculiar subclass of active galactic nuclei (AGN). Among them, TXS 1206+549 belongs to a small group of radio-loud and gamma-ray-emitting NLS1 galaxies. We focus on the radio properties of this…
A complete flat-spectrum radio-loud sample of AGN includes a significant fraction of Seyfert-like AGN including a NLS1. Analysis of their optical spectra suggests that the reddest continuum colours are either associated with AGN in nearby…
Narrow-line Seyfert 1 galaxies (NLS1s) are generally known to be radio-quiet Active Galactic Nuclei (AGN), but a tiny subset of them are found to be extremely radio-loud with radio loudness parameter ($R_{\rm 1.4~GHz}$) $>$ 100. Given their…
The masses of central supermassive black holes in a soft X-ray selected sample of the narrow-line Seyfert 1 galaxies (NLS1s) are estimated by some different methods to test their theoretical models. Apart from the methods using the H$\beta$…
Reverberation from scattering material around the black hole in active galactic nuclei is expected to produce a characteristic signature in a Fourier analysis of the time delays between directly-viewed continuum emission and the scattered…
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.…