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Compton Thick (CT) AGN are a key ingredient of Cosmic X-ray Background (CXB) synthesis models, but are still an elusive component of the AGN population beyond the local Universe. Multi-wavelength surveys are the only way to find them at z >…

Astrophysics of Galaxies · Physics 2017-05-10 G. Lanzuisi

While theory and simulations indicate that galaxy mergers play an important role in the cosmological evolution of accreting black holes and their host galaxies, samples of Active Galactic Nuclei (AGN) in galaxies at close separations are…

We have conducted an extensive X-ray spectral variability study of a sample of 20 Compton-thin type II galaxies using broad band spectra from XMM-Newton, Chandra, and Suzaku. The aim is to study the variability of the neutral intrinsic…

Astrophysics of Galaxies · Physics 2020-07-15 Sibasish Laha , Alex G. Markowitz , Mirko Krumpe , Robert Nikutta , Richard Rothschild , Tathagata Saha

We present new photometry of 16 local Seyferts including 6 Compton-thick sources in N-band filters around 12-microns, obtained with the VISIR instrument on the 8-m Very Large Telescope. The near-diffraction-limited imaging provides the…

Astrophysics of Galaxies · Physics 2015-05-13 P. Gandhi , H. Horst , A. Smette , S. Hoenig , A. Comastri , R. Gilli , C. Vignali , W. Duschl

We present the combined NuSTATR and XMM-Newton 0.6-79 keV spectral analysis of a Seyfert 2 galaxy, NGC 1358, which we selected as a candidate Compton thick (CT-) active galactic nucleus (AGN) on the basis of previous Swift/BAT and Chandra…

Astrophysics of Galaxies · Physics 2019-01-16 X. Zhao , S. Marchesi , M. Ajello , L. Marcotulli , G. Gusumano , V. La Parola , C. Vignali

"Changing look" Active Galactic Nuclei (AGN) are a subset of Seyfert galaxies characterized by rapid transitions between Compton-thin and Compton-thick regimes. In their Compton-thin state, the central engine is less obscured, hence…

High Energy Astrophysical Phenomena · Physics 2013-09-09 Frederic Marin , Delphine Porquet , Rene W. Goosmann , Michal Dovciak , Fabio Muleri , Nicolas Grosso , Vladimir Karas

Active galactic nuclei (AGN) are powerful sources of panchromatic radiation. All AGN emit in X-rays, contributing around $\sim 5-10\%$ of the AGN bolometric luminosity. The X-ray emitting region, popularly known as the corona, is…

High Energy Astrophysical Phenomena · Physics 2024-12-24 Sibasish Laha , Claudio Ricci , John C. Mather , Ehud Behar , Luigi C. Gallo , Frederic Marin , Rostom Mbarek , Amelia Hankla

We present the distributions of geometrical covering factors of active galactic nuclei (AGNs) dusty tori (f2) using an X-ray selected complete sample of 227 AGN drawn from the Bright Ultra-hard XMM-Newton Survey. The AGN have z from 0.05 to…

We present the results of a systematic, broadband X-ray spectral analysis of nearby active galactic nuclei (AGNs) with the X-ray clumpy torus model (XCLUMPY; Tanimoto et al. 2019). By adding 16 AGNs newly analyzed in this paper, we study…

High Energy Astrophysical Phenomena · Physics 2021-01-20 Shoji Ogawa , Yoshihiro Ueda , Atsushi Tanimoto , Satoshi Yamada

At energies ~>2 keV, active galactic nuclei (AGN) are the source of the cosmic X-ray background (CXB). For AGN population synthesis models to replicate the peak region of the CXB (~30 keV), a highly obscured and therefore nearly invisible…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-20 A. R. Draper , D. R. Ballantyne

We present a detailed X-ray spectral analysis of 1152 AGNs selected in the Chandra Deep Fields (CDFs), in order to identify highly obscured AGNs ($N_{\rm H} > 10^{23}\ \rm cm^{-2}$). By fitting spectra with physical models, 436 (38%)…

For measurement of the AGN luminosity function and its evolution, X-ray selection samples all types of AGN and provides reduced obscuration bias in comparison with UV-excess or optical surveys. The apparent decline in optically-selected…

We present results from the fitting of infrared (IR) spectral energy distributions of 21 active galactic nuclei (AGN) with clumpy torus models. We compiled high spatial resolution ($\sim 0.3$--$0.7$ arcsec) mid-IR $N$-band spectroscopy,…

We present the first direct measurements of the rest-frame 10-40 keV X-ray luminosity function (XLF) of Active Galactic Nuclei (AGNs) based on a sample of 94 sources at 0.1 < z <3, selected at 8-24 keV energies from sources in the NuSTAR…

The recent Chandra discovery of extended $\sim$kpc-scale hard ($>$ 3 keV) X-ray emission in nearby Compton-thick (CT) active galactic nuclei (AGN) opens a new window to improving AGN torus modeling and investigating how the central super…

Astrophysics of Galaxies · Physics 2020-08-06 Jingzhe Ma , Martin Elvis , G. Fabbiano , Mislav Balokovic , W. Peter Maksym , Mackenzie L. Jones , Guido Risaliti

Broadband X-ray spectroscopy of the X-ray emission produced in the coronae of active galactic nuclei (AGN) can provide important insights into the physical conditions very close to their central supermassive black holes. The temperature of…

We present the analysis of multiepoch observations of a set of 12 variable, Compton-thin, local (z<0.1) active galactic nuclei (AGN) selected from the 100-month BAT catalog. We analyze all available X-ray data from \chandra, \xmm, and…

Astrophysics of Galaxies · Physics 2023-10-18 N. Torres-Albà , S. Marchesi , X. Zhao , I. Cox , A. Pizzetti , M. Ajello , R. Silver

Narrow-band spectral imaging with sub-pixel resolution of the Chandra-ACIS archival observation of the ULIRG merger Arp 220 strongly suggests two Compton thick nuclei, spatially coincident with the infrared and radio emitting nuclear…

High Energy Astrophysical Phenomena · Physics 2013-03-12 Alessandro Paggi , Giuseppina Fabbiano , Guido Risaliti , Junfeng Wang , Martin Elvis

According to theory, the torus of active galactic nuclei (AGN) is sustained from a wind coming off the accretion disk, and for low efficient AGN, it has been proposed that such structure disappears. However, the exact conditions for its…

Explicit 2-d axisymmetric solutions are found to the hydrostatic equilibrium, energy balance, and photon diffusion equations within obscuring tori around active galactic nuclei. These solutions demonstrate that infrared radiation pressure…

Astrophysics · Physics 2011-02-11 Julian H. Krolik