Related papers: Steep Spectrum Seyfert Galaxies
We present a detailed timing and spectral study of an extremely variable narrow-line Seyfert~1 galaxy NGC 4748 using observations in the year 2017 and 2014 performed with AstroSat and XMM-Newton, respectively. Both observations show…
We have studied the average 3-200 keV spectra of Seyfert galaxies of type 1 and 2, using data obtained with BeppoSAX. The average Seyfert 1 spectrum is well-fitted by a power law continuum with photon spectral index Gamma~1.9, a Compton…
The Unified Model of AGN predicts the sole difference between Seyfert 1 and Seyfert 2 nuclei is the viewing angle with respect to an obscuring structure around the nucleus. High energy photons above 20 keV are not affected by this…
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…
The spectroscopic properties of the objects that came to be called Narrow-Line Seyfert 1s were first systematically described and named as such 15 years ago by Osterbrock & Pogge (1985). At the time, they were a relatively rare and peculiar…
We report results from a Suzaku observation of the narrow-line Seyfert 1 NGC 4051. During our observation, large amplitude rapid variability is seen and the averaged 2--10 keV flux is 8.1x10^-12 erg s^-1 cm^-2, which is several times lower…
Studying simultaneous optical and X-ray light curves of radio-quiet AGN can help to probe the relationship between very different physical components - the cool, optically thick disk and hot, optically thin corona. Here, we review the…
We review observations and theoretical models of X-ray/gamma-ray spectra of radio-quiet Seyfert galaxies and of Galactic black-hole candidates (in the hard spectral state). The observed spectra share all their basic components: an…
We present broad band Suzaku}observations of a small sample of hard X-ray selected (> 10 keV), nearby Seyfert 2 galaxies and discuss the results in the context of AGN unified model. We also review the issues related to the space density of…
We identify 175 Seyfert galaxies from the Southern Sky Redshift Survey - SSRS2. We use the entire SSRS2 catalog to investigate the correlation between the presence of AGN with host environment. The AGN phenomenon is more strongly correlated…
I provide a short review of the properties of Narrow-line Seyfert 1 (NLS1) galaxies across the electromagnetic spectrum and of the models to explain them. Their continuum and emission-line properties manifest one extreme form of Seyfert…
We present and discuss the properties of a complete and well defined sample of X-ray selected type 1 AGNs including 26 Narrow-Line Seyfert 1 and 129 Broad-Line Seyfert 1 galaxies derived from the XMM-Newton Bright Serendipitous Survey…
BeppoSAX observations of Broad Line Radio Galaxies (BLRGs) have shown that they have a considerable variety of spectral properties and important differences with respect to their radio-quiet counter-part Seyfert 1s. In radio galaxies the…
We present new spectropolarimetry of a sample of nearby Compton-thin Seyfert 2 galaxies (ie those with N_H<10^23 cm^-2). We show that the detection rate of scattered broad Halpha in this sample is considerably higher than in Seyfert 2…
Using the VLT together with the near infrared instrument ISAAC, we have obtained medium spectral and high spatial resolution observations of a sample of nearby Seyfert galaxies in the H-band. This band is particularly suited for stellar…
We present the Spitzer 10-37um IRS high resolution (R~600) spectroscopic survey of the Seyfert galaxies of the 12 micron Galaxy Sample. The new spectra of 61 galaxies, with those already published, gives us a total of 91 12micron Seyfert…
We present a composite 1-10 keV Seyfert 2 X-ray spectrum, derived from ASCA observations of a distance-limited sample of nearby galaxies. All 29 observed objects were detected. Above ~3 keV, the composite spectrum is inverted, confirming…
We present results from RXTE data obtained during a systematic monitoring program of four Seyfert galaxies (NGC5548, NGC5506, MCG-6-30-15 and NGC4051). We studied the variability of three hardness ratios derived from the light curves in…
A fraction of active galactic nuclei do not show the classical Seyfert-type signatures in their optical spectra, i.e. they are optically "elusive". X-ray observations are an optimal tool to identify this class of objects. We combine new…
We report the results of near infrared observations of 19 soft X-ray selected AGN. The goal of the observations was to search for strong, narrow Paschen-alpha or Brackett-gamma emission lines, as a sign of nuclear starbursts. We found…