Related papers: Seyfert galaxies: Nuclear Radio Structure and Unif…
We report on a multiwavelength survey of a sample of 42 flat-spectrum radio-loud narrow-line Seyfert 1 galaxies (RLNLS1s). This is the largest known sample of this type of active galactic nucleus (AGN) to date. We found that 17% of sources…
We present the first data release of high-resolution ($\leq0.2$ arcsec) 1.5-GHz radio images of 103 nearby galaxies from the Palomar sample, observed with the eMERLIN array, as part of the LeMMINGs survey. This sample includes galaxies…
We have detected six narrow-line Seyfert 1 (NLS1) galaxies at 37 GHz that were previously classified as radio silent and two that were classified as radio quiet. These detections reveal the presumption that NLS1 galaxies labelled radio…
We analyzed a large sample of SDSS spectra of Seyfert galaxies, subdividing Seyfert 1s based on their narrow-to-broad Halpha components. Comparing their narrow-lines (NL) to Seyfert2s in line-ratio diagrams, most of the NL of strong Sy 1.0…
We report the results from a six-year, multi-epoch very long baseline interferomertry monitoring of the Seyfert galaxy NGC3079. We have observed NGC3079 during eight epochs between 1999 and 2005 predominantly at 5GHz, but covering the…
We present the results of VLA A-array 8.46 GHz continuum imaging of 55 Seyfert galaxies (19 Seyfert 1's and 36 Seyfert 2's). These galaxies are part of a larger sample of 88 Seyfert galaxies, selected from mostly isotropic properties, the…
Far-infrared flux densities are newly extracted from the IRAS database for the RSA and CfA complete samples of Seyfert galaxies. These data are used to classify the Seyfert galaxies into those where the far-infrared continuum emission is…
Powerful, large-scale relativistic jets are usually associated with massive, old elliptical galaxies. This paradigm has recently been challenged by the identification of narrow-line Seyfert 1 (NLSy1) galaxies, thought to be young active…
The first short part of this review is a general, but very detailed, critique of the literature advocating a class of Seyfert galaxies intrinsically lacking broad emission lines. My conclusion is that there is little or no evidence for such…
We use hard X-ray data for an "optimal" sample of Seyfert 2 galaxies to derive the distribution of the gaseous absorbing column densities among obscured active nuclei in the local Universe. Of all Seyfert 2 galaxies in the sample, 75% are…
While NLS1s have been studied intensively at X-ray and optical wavelengths, comparatively little is known about their characteristics in the radio band. Therefore, we have carried out an investigation of the radio luminosities, source…
Narrow-line Seyfert 1 (NLS1) galaxies provide us with unique insights into the drivers of AGN activity under extreme conditions. Given their low black hole (BH) masses and near-Eddington accretion rates, they represent a class of galaxies…
Narrow-line Seyfert 1 (NLS1) galaxies are believed to be active galactic nuclei (AGN) in the early stages of their evolution. Some dozens of them have been found to host relativistic jets, whilst the majority has not even been detected in…
We are conducting a multi-wavelength (radio, optical, and X-ray) observational campaign to classify, morphologically and physically, a sample of 55 flat-spectrum radio sources dominated by structure on kpc-scales. This sample contains 22…
In the last decade of Active Galactic Nuclei (AGN) monitoring programs, the Mets\"ahovi Radio Observatory detected multiple times seven powerful flaring narrow-line Seyfert 1 (NLS1) galaxies at 37 GHz. Several hypotheses have been proposed,…
The Unified Model of Active Galactic Nuclei (AGN) has provided a successful explanation for the observed diversity of AGN in the local Universe. However, recent analysis of multi-wavelength spectral and image data suggests that the Unified…
We present the results of a program of K- and Ks-band imaging of a sample of 2Jy radio galaxies with redshifts 0.03 < z < 0.5, for which the host galaxy morphologies and structural parameters (effective radius, Sersic index and unresolved…
The origin of the radio emission in active galactic nuclei (AGN) is still debated. Multiple physical mechanisms can contribute to the spectrum at these frequencies, including relativistic jets, the jet base, outflows, star formation, and…
We present the first results of a radio survey of 79 narrow-line Seyfert 1 (NLS1) carried out with the Karl G. Jansky Very Large Array (JVLA) at 5 GHz in A configuration aimed at studying the radio properties of these sources. We report the…
We have discovered kiloparsec-scale extended radio emission in three narrow-line Seyfert 1 galaxies (NLS1s) in sub-arcsecond resolution 9 GHz images from the Karl G. Jansky Very Large Array (VLA). We find all sources show two-sided, mildly…