Related papers: Steep Spectrum Seyfert Galaxies
RE J2248-511 is one of only 14 non-blazar AGN detected in the far ultraviolet by the ROSAT Wide Field Camera implying a large ultrasoft X-ray flux. This soft X-ray excess is strongly variable on year timescales, a common property of Narrow…
We have discovered a Narrow-Line Seyfert 1 (NLS1) galaxy and identified it with an ultrasoft X-ray source RX 215319-1514 detected with ROSAT. We present its X-ray and optical spectral characteristics. Its redshift is found to be…
We present the optical spectra and simple statistical analysis for a complete sample of 110 soft X-ray selected AGN. About half of the sources are Narrow-Line Seyfert 1 galaxies (NLS1s), which have the steepest X-ray spectra, strongest FeII…
Preliminary results are presented for a spectroscopic survey of the Groth Survey Strip (GSS), a 40 by 3.5 arcminute region of the sky imaged with HST, for which several hundred galaxy spectra have been obtained as part of the DEEP project…
Recent ASCA and ROSAT X-ray observations of active galaxies have revealed a host of new data on the fundamental properties of active galaxies. Amongst these are the discovery and characterization of absorption by ionized gas in Seyfert-I…
We present preliminary results of the analysis of optical spectra of two complementary samples of Seyfert galaxies. The first sample was extracted from a selection of the 4th Fermi Gamma-ray Large Area Telescope (4FGL) catalog, and consists…
We have examined ROSAT soft X-ray observations of a complete, distance-limited sample of Seyfert and LINER galaxies. X-ray data are available for 46 out of 60 such objects which lie within a hemisphere of radius 18 Mpc. We have constructed…
Obscured active galactic nuclei, which are classified optically as type 2 (narrow-line) Seyfert galaxies in the local universe, are by far the most promising candidates for the origin of the hard (2-10 keV) X-ray background radiation.…
The Seyfert 1.9 galaxy MCG-05-23-016 has been shown to exhibit a complex X-ray spectrum. This source has moderate X-ray luminosity, hosts a comparably low-mass black hole, but accretes at a high Eddington rate, and allows us to study a…
The ROSAT Bright Survey (RBS) aims to completely optically identify the more than 2000 brightest sources detected in the ROSAT all-sky survey at galactic latitudes |b| > 30 degr (excluding LMC, SMC, Virgo cluster). This paper presents a…
The Swift Burst Alert Telescope (BAT) survey of Active Galactic Nuclei (AGN) is providing an unprecedented view of local AGNs (<z> = 0.03) and their host galaxy properties. In this paper, we present an analysis of the optical spectra of a…
Using the latest 70 month Swift-BAT catalog we examined hard X-ray selected Seyfert I galaxies which are relatively little known and little studied, and yet potentially promising to test the ionized relativistic reflection model. From this…
We analyze X-ray spectra and images of a sample of Seyfert 2 galaxies that unambiguously contain starbursts, based on their optical and UV characteristics. Although all sample members contain active galactic nuclei (AGNs), supermassive…
The advent of the Very Long Baseline Array and its phase-referencing capability have enabled milliarcsecond-scale imaging of radio sources at sub-millijansky sensitivity, opening the door to high-resolution imaging of Seyfert galaxies. Over…
We study the properties of warm absorbers in several active galaxies (AGN) and present new candidates, using ROSAT X-ray observations. Several aspects of the characteristics of warm absorbers are discussed, constraints on the density and…
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,…
In order to study systematically the soft X-ray emission of Active Galactic Nuclei (AGNs) at medium to high redshifts, we have analyzed ROSAT PSPC and HRI data of QSOs at 0.26<z<3.43 selected from the second deepest ROSAT PSPC survey…
This paper presents a quantification of the X-ray variability amplitude for 79 ASCA observations of 36 Seyfert 1 galaxies. We find that consideration of sources with the narrowest permitted lines in the optical band introduces scatter into…
We present ASCA data on RE J2248-511, extending existing optical and soft X-ray coverage to 10 keV, and monitoring the soft component. These data show that, despite a very strong ultrasoft X-ray excess below 0.3 keV and a soft 0.3--2 keV…
The rapid and seemingly random fluctuations in X-ray luminosity of Seyfert galaxies provided early support for the standard model in which Seyferts are powered by a supermassive black hole fed from an accretion disc. However, since EXOSAT…