Related papers: Scattered X-rays in Obscured Active Galactic Nucle…

We study the hard-X-ray spectral properties of ten highly luminous radio-quiet (RQ) active galactic nuclei (AGNs) at z=1.3-3.2, including new XMM-Newton observations of four of these sources. We find a significant correlation between the…

Centaurus A (Cen A) is the closest radio galaxy and a prime example of a low-luminosity active galactic nucleus (AGN), exhibiting complex emissions across the electromagnetic spectrum. The nature of its continuum emission, particularly the…

We analyze X-ray spectra of heavily obscured (N_H > 10^{24} cm^{-2}) active galaxies obtained with Chandra, concentrating on the iron K alpha fluorescence line. We measure very large equivalent widths in most cases, up to 5 keV in the most…

The "torus" obscurer of Active Galactic Nuclei (AGN) is poorly understood in terms of its density, substructure and physical mechanisms. Large X-ray surveys provide model boundary constraints, for both Compton-thin and Compton-thick levels…

We compiled a sample of 95 AGNs serendipitously detected in the 3-20 keV band at Galactic latitude |b|>10 during the RXTE slew survey (XSS, Revnivtsev et al.), and utilize it to study the statistical properties of the local population of…

AGN are known to have complex X-ray spectra that depend on both the properties of the accreting SMBH (e.g. mass, accretion rate) and the distribution of obscuring material in its vicinity ("torus"). Often however, simple and even unphysical…

X-ray variability is a well-established characteristic of active galactic nuclei (AGN), known to correlate inversely with both the supermassive black hole mass and luminosity, although the degree of each remains a topic of debate. The…

We present a sample of twenty-one ROSAT bright active galactic nuclei (AGN), representing a range of spectral classes, and selected for follow-up snap-shot observations with XMM-Newton. The typical exposure was between 5-10 ks. The objects…

We use a combination of the XMM-Newton serendipitous X-ray survey with the optical SDSS, and the infrared WISE all-sky survey in order to check the efficiency of the low X-ray to infrared luminosity selection method in finding heavily…

Striking similarities have been seen between accretion signatures of Galactic X-ray binary (XRB) systems and active galactic nuclei (AGN). XRB spectral states show a V-shaped correlation between X-ray spectral hardness and Eddington ratio…

We present a broadband X-ray analysis of a new homogeneous sample of 95 active galactic nuclei (AGN) from the 22-month Swift/BAT all-sky survey. For this sample we treated jointly the X-ray spectra observed by XMM-Newton and INTEGRAL…

X-ray spectroscopy offers an opportunity to study the complex mixture of emitting and absorbing components in the circumnuclear regions of active galactic nuclei, and to learn about the accretion process that fuels AGN and the feedback of…

We have completed a spectroscopic survey of X-ray point sources in eight low-redshift clusters of galaxies (0.05<z<0.31) and have identified 40 cluster members with broad-band (0.3-8 keV) X-ray luminosities between L_X = 8x10^{40} and…

We present spectra of the nuclear regions of 50 nearby (D = 1 - 92 Mpc, median = 20 Mpc) galaxies of morphological types E to Sm. The spectra, obtained with the Gemini Near-IR Spectrograph on the Gemini North telescope, cover a wavelength…

The incidence and properties of Active Galactic Nuclei (AGN) in the field, groups, and clusters can provide new information about how these objects are triggered and fueled, similar to how these environments have been employed to study…

Detection of absorbed active galactic nuclei and their properties remains an elusive and important problem in understanding the evolution and activation of black holes. With the very hard X-ray survey conducted by Swift's Burst Alert…

We adopt a Bayesian X-ray spectral approach to investigate the accretion properties of unobscured ($20<\log(N_{\rm H}/{\rm cm}^{-2}<22$) and obscured ($22< \log(N_{\rm H}/{\rm cm}^{-2}<24$) active galactic nuclei (AGN) to shed light on the…

Monte Carlo simulation is one of the best tools to study the complex spectra of Compton-thick AGNs and to figure out the relation between their nuclear structures and X-ray spectra. We have simulated X-ray spectra of Compton-thick AGNs…

The infrared is a key wavelength regime for probing the dusty, obscured nuclear regions of active galaxies. We present results from an infrared study of 87 nearby Seyfert galaxies using the Spitzer Space Telescope and ground-based…

We compiled a sample of 73 active galactic nuclei (AGNs) with reverberation mapping (RM) observations from RM campaigns including our ongoing campaign of monitoring super-Eddington accreting massive black holes (SEAMBHs). This sample covers…