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We study the comoving space density of X-ray-selected luminous active galactic nuclei (AGNs) and the obscured AGN fraction at high redshifts ($3 < z < 5$) in the Subaru/{\it XMM-Newton} Deep Survey (SXDS) field. From an X-ray source catalog…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 Kazuo Hiroi , Yoshihiro Ueda , Masayuki Akiyama , Mike G. Watson

A tight correlation between nuclear millimeter (mm) and X-ray emission has recently been found in nearby ($z < 0.01$) and low-Eddington ratio ($\rm \lambda_{Edd} < 0.1$) radio-quiet (RQ) Active Galactic Nuclei (AGN), suggesting a common…

We present one of the largest multiwavelength studies of simultaneous optical-to-X-ray spectral energy distributions (SEDs) of unobscured active galactic nuclei (AGN) in the local Universe. Using a representative sample of…

In this paper, we explained the observed $\Gamma_{\rm 2-10keV}-L_{\rm bol}/L_{\rm Edd}$ correlation in luminous active galactic nuclei within the framework of the condensation of the corona around a supermassive black hole (Liu et al. 2015;…

High Energy Astrophysical Phenomena · Physics 2018-03-28 Erlin Qiao , B. F. Liu

We present a unification model for a clumpy obscurer in active galactic nuclei (AGN) and investigate the properties of the resulting X-ray spectrum. Our model is constructed to reproduce the column density distribution of the AGN population…

High Energy Astrophysical Phenomena · Physics 2019-09-04 Johannes Buchner , Murray Brightman , Kirpal Nandra , Robert Nikutta , Franz E. Bauer

We present a new method to predict the line-of-sight column density (NH) values of active galactic nuclei (AGN) based on mid-infrared (MIR), soft, and hard X-ray data. We developed a multiple linear regression machine learning algorithm…

Astrophysics of Galaxies · Physics 2023-07-05 Ross Silver , Núria Torres-Alba , Xiurui Zhao , Stefano Marchesi , Andrealuna Pizzetti , Isaiah Cox , Marco Ajello

Chandra and XMM-Newton have resolved the 2-8 keV X-ray Background (XRB) into point sources. Many of the fainter sources are obscured active galactic nuclei (AGN) with column densities in the range of 10^22-10^23 pcmsq, some of which have…

Astrophysics · Physics 2009-11-07 A. C. Fabian , R. J. Wilman , C. S. Crawford

We present the results of the X-ray polarimetric analyses performed on unobscured radio-quiet Active Galactic Nuclei (AGN) with the Imaging X-ray Polarimetry Explorer (IXPE), with simultaneous XMM-Newton and NuSTAR data. The synergy of…

Astrophysics of Galaxies · Physics 2024-07-01 V. E. Gianolli , S. Bianchi , P-O. Petrucci , A. Marinucci , A. Ingram , D. Tagliacozzo , D. E. Kim , F. Marin , G. Matt , P. Soffitta , F. Tombesi

We studied the broadband X-ray spectra of {\it Swift}/BAT selected low-accreting AGNs using the observations from {\it XMM-Newton}, {\it Swift}, and {\it NuSTAR} in the energy range of $0.5-150$~keV. Our sample consists of 30 AGNs with…

High Energy Astrophysical Phenomena · Physics 2023-07-26 Arghajit Jana , Arka Chatterjee , Hsiang-Kuang Chang , Prantik Nandi , Rubinur K. , Neeraj Kumari , Sachindra Naik , Samar Safi-Harb , Claudio Ricci

We examine the accretion properties in a sample of 42 hard (3-60keV) X-ray selected nearby broad-line AGNs. The energy range in the sample is harder than that usually used in the similar previous studies. These AGNs are mainly complied from…

Astrophysics · Physics 2011-02-19 J. Wang , Y. F. Mao , J. Y. Wei

This work attempts to provide a new interpretation for the hot corona in active galactic nuclei (AGNs). A thin parabolic magnetic reconnection layer, anchored at the innermost disk and extending along the boundary of the magnetic tower for…

High Energy Astrophysical Phenomena · Physics 2025-02-04 Yu Zhao , Yan-Rong Li , Jian-Min Wang

We present a systematic X-ray and multiwavelength study of a sample of 47 active galactic nuclei (AGNs) with reverberation-mapping measurements. This sample includes 21 super-Eddington accreting AGNs and 26 sub-Eddington accreting AGNs.…

Astrophysics of Galaxies · Physics 2021-04-07 Hezhen Liu , B. Luo , W. N. Brandt , Michael S. Brotherton , S. C. Gallagher , Q. Ni , Ohad Shemmer , J. D. Timlin

To fully understand cosmic black hole growth we need to constrain the population of heavily obscured active galactic nuclei (AGN) at the peak of cosmic black hole growth ($z\sim$1-3). Sources with obscuring column densities higher than…

High Energy Astrophysical Phenomena · Physics 2017-08-02 L. Baronchelli , M. Koss , K. Schawinski , C. Cardamone , F. Civano , A. Comastri , M. Elvis , G. Lanzuisi , S. Marchesi , C. Ricci , M. Salvato , B. Trakhtenbrot , E. Treister

Obscuration in active galactic nuclei (AGN) provides insights into the material surrounding the central engine. Compton-thick AGN (CTAGN), characterized by a column density of $N_{\mathrm{H}} \geq 1.5 \times 10^{24} \ \mathrm{cm}^{-2}$, are…

Astrophysics of Galaxies · Physics 2025-04-03 M. L. H. Musa , Z. Z. Abidin , A. Annuar , D. A. A. Lee

(Abridged) We present the results from the X-ray spectral analysis of high-z AGN in the CDFS, making use of the new 4Ms data set and new X-ray spectral models from Brightman & Nandra, which account for Compton scattering and the geometry of…

High Energy Astrophysical Phenomena · Physics 2015-06-04 Murray Brightman , Yoshihiro Ueda

X-ray emission from AGN is believed to be produced via Comptonization of optical/UV seed photons emitted by the accretion disk, up-scattered by hot electrons in a corona surrounding the black hole. A critical compactness vs. temperature…

Active galactic nuclei (AGN) are complex phenomena. At the heart of an AGN is a relativistic accretion disk around a spinning supermassive black hole (SMBH) with an X-ray emitting corona and, sometimes, a relativistic jet. On larger scales,…

High Energy Astrophysical Phenomena · Physics 2016-05-25 Christopher S. Reynolds

This paper presents a survey of X-ray selected active galactic nuclei (AGN) with optical spectroscopic follow-up in a $\sim 18\, \rm{deg^2}$ area of the equatorial XMM-XXL north field. A sample of 8445 point-like X-ray sources detected by…

A complete census of Active Galactic Nuclei (AGN) is a prerequisite for understanding the growth of supermassive black holes across cosmic time. A significant challenge toward this goal is the whereabouts of heavily obscured AGN that remain…

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…