Related papers: Radio Variability in Seyfert Nuclei
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…
We present more than three years of observations at different frequencies, from radio to high-energy gamma-rays, of the Narrow-Line Seyfert 1 (NLS1) Galaxy PMN J0948+0022 (z=0.585). This source is the first NLS1 detected at energies above…
We present radio observations for 29 southern Seyfert galaxies selected from a volume limited sample with cz<3600 km s^-1, and declination delta<0degr. Objects with declination -30degr<delta<0degr were observed with the Very Large Array…
We present the analysis of X-ray spectral varability made on a sample of 7 Seyfert 1 bright galaxies, using XMM-Newton data. From the "XMM-Newton Science Archive" we selected those bright Seyfert 1 showing one or more prominent flares in…
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 nearby face-on spiral galaxy NGC 2617 underwent an unambiguous 'inside-out' multi-wavelength outburst in Spring 2013, and a dramatic Seyfert type change probably between 2010 and 2012, with the emergence of broad optical emission lines.…
We use the difference (delta) between the position angles of the nuclear radio emission and the host galaxy major axis to investigate the distribution of the angle (beta) between the axes of the nuclear accretion disk and the host galaxy…
We study the variability properties at radio frequencies of the jets thought to be typical of Active Galactic Nuclei, i.e. bulk Lorentz factor \Gamma ~ 10, and incoherent synchrotron emission. We assume that the radiating electrons are…
We present the results of a 2-epoch variability survey in the Hubble Deep Field with the goal of investigating the population of AGN to z=1. The primary data sets analyzed for galactic variability are the original HDF observations obtained…
Because the disc--jet coupling likely depends on various properties of sources probed, the sample control is always an important but challenging task. In this work, we re-analyzed the INTEGRAL hard X-ray-selected sample of Seyfert galaxies.…
We present the results of timing analysis of the XMM-Newton observation of the Seyfert 2 galaxy NGC 6300. The hard X-ray spectrum above 2 keV consists of a Compton-thin-absorbed power law, as is often seen in Seyfert 2 galaxies. We clearly…
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…
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…
Observations at 37 GHz, performed at Mets\"ahovi Radio Observatory, are presented for a sample of 78 radio-loud and radio-quiet narrow-line Seyfert 1 (NLS1) galaxies, together with additional lower and higher frequency radio data from…
We have used the Very Large Array (VLA) to conduct a survey for radio continuum emission in the sample of 52 Seyfert nuclei selected from the optical spectroscopic galaxy catalog of Ho, Filippenko, and Sargent. This Seyfert sample is the…
We present results of multicolor UBVRI observations of the type 1 Seyfert galaxy (SyG 1) NGC 7469 carried out at the 1.5-meter telescope of the Maidanak Observatory (Uzbekistan) in 2008-2014. Analysis of the light curves indicates the…
We present the results of an intensive ultraviolet monitoring campaign on the Seyfert 1 galaxy NGC 4151, as part of an effort to study its short time-scale variability over a broad range in wavelength. The nucleus of NGC 4151 was observed…
This paper combines data from the three preceding papers in order to analyze the multi-waveband variability and spectral energy distribution of the Seyfert~1 galaxy NGC~4151 during the December 1993 monitoring campaign. The source, which…
We present slitless spectra of 10 Seyfert galaxies observed with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope. The spectra cover the [OIII] 4959, 5007 emission lines at a spectral resolving power of ~9000 and a…
Study of high-redshift radio galaxies (HzRGs) can shed light on the active galactic nuclei (AGNs) evolution in massive elliptical galaxies. The vast majority of observed high-redshift AGNs are quasars, and there are very few radio galaxies…