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Understanding how active galactic nuclei (AGN) affect their host galaxies requires determining their total radiative power across all wavelengths (i.e., bolometric luminosities). We show how AGN accretion disk spectral energy distribution…

Astrophysics of Galaxies · Physics 2025-09-25 Mojegan Azadi , Belinda Wilkes , Joanna Kuraszkiewicz , Steven. P. Willner , Matthew L. N. Ashby

A large population of heavily obscured, Compton Thick AGNs is predicted by models of galaxy formation, models of Cosmic X-ray Background and by the ``relic'' super-massive black-hole mass function measured from local bulges. However, so far…

We analyze the Spitzer spectra of 140 active galactic nuclei (AGN) detected in the hard X-rays (14-195 keV) by the Burst Alert Telescope (BAT) on board Swift. This sample allows us to probe several orders of magnitude in black hole masses…

We present the spatial analysis of five Compton thick (CT) active galactic nuclei (AGNs), including MKN 573, NGC 1386, NGC 3393, NGC 5643, and NGC 7212, for which high resolution Chandra observations are available. For each source, we find…

Astrophysics of Galaxies · Physics 2021-03-31 Mackenzie L Jones , K. Parker , G. Fabbiano , M. Elvis , W. P. Maksym , A. Paggi , J. Ma , M. Karovska , A. Siemiginowska , J. Wang

We perform long-term ($\approx 15$ yr, observed-frame) X-ray variability analyses of the 68 brightest radio-quiet active galactic nuclei (AGNs) in the 6 Ms $Chandra$ Deep Field-South (CDF-S) survey; the majority are in the redshift range of…

High Energy Astrophysical Phenomena · Physics 2016-11-09 G. Yang , W. Brandt , B. Luo , Y. Xue , F. Bauer , M. Sun , S. Kim , S. Schulze , X. Zheng , M. Paolillo , O. Shemmer , T. Liu , D. Schneider , C. Vignali , F. Vito , J. -X. Wang

AGN exhibit complex hard X-ray spectra. Our current understanding is that the emission is dominated by inverse Compton processes which take place in the corona above the accretion disk, and that absorption and reflection in a distant…

High Energy Astrophysical Phenomena · Physics 2009-06-25 V. Beckmann , T. J. -L. Courvoisier , N. Gehrels , P. Lubinski , J. Malzac , P. O. Petrucci , C. R. Shrader , S. Soldi

Even in deep X-ray surveys, Compton-thick active galactic nuclei (CT AGNs, ${\rm N_H} \geqslant 1.5~\times~10^{24}~{\rm cm}^{-2}$) are difficult to be identified due to X-ray flux suppression and their complex spectral shape. However, the…

Astrophysics of Galaxies · Physics 2021-03-03 Xiaotong Guo , Qiusheng Gu , Nan Ding , Xiaoling Yu , Yongyun Chen

Compton-thick active galactic nuclei (CT-AGNs), which are defined by column density $\mathrm{N_H} \geqslant 1.5 \times 10^{24} \ \mathrm{cm}^{-2}$, emit feeble X-ray radiation, even undetectable by X-ray instruments. Despite this, the X-ray…

Astrophysics of Galaxies · Physics 2025-05-28 Rui Zhang , Xiaotong Guo , Qiusheng Gu , Guanwen Fang , Jun Xu , Hai-Cheng Feng , Yongyun Chen , Rui Li , Nan Ding , Hongtao Wang

We present the observed-frame optical, near- and mid-infrared properties of X-ray selected AGN in the Lockman Hole. Using a likelihood ratio method on optical, near-infrared or mid-infrared catalogues, we assigned counterparts to 401 out of…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 E. Rovilos , S. Fotopoulou , M. Salvato , V. Burwitz , E. Egami , G. Hasinger , G. Szokoly

Within the framework of our program of assessment of the nature of unidentified or poorly known INTEGRAL sources, we present here spectroscopy of optical objects, selected through positional cross-correlation with soft X-ray detections…

[Abridged]We report on the broadband X-ray properties of a complete sample of absorbed Seyfert galaxies hard X-ray selected with INTEGRAL. The sample is composed of 33 sources: 15 are newly discovered above 20 keV while 18 are already known…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 A. De Rosa , F. Panessa , L. Bassani , A. Bazzano , A. Bird , R. Landi , A. Malizia , M. Molina , P. Ubertini

We present a study of optically selected dual AGN with projected separations of 3--97~kpc. Using multi-wavelength (MWL) information (optical, X-rays, mid-IR), we characterized the intrinsic nuclear properties of this sample and compared…

As the mid-IR luminosity represents a good isotropic proxy of the AGN power, a low X-ray to mid-IR luminosity ratio is often claimed to be a reliable indicator for selecting Compton-thick (CT) AGN. We assess the efficiency of this…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 I. Georgantopoulos , E. Rovilos , A. Akylas , A. Comastri , P. Ranalli , C. Vignali , I. Balestra , R. Gilli , N. Cappelluti

(abridged) We take advantage of the deep Chandra and Spitzer coverage of a large area (more than 10 times the area covered by the Chandra deep fields, CDFs in the COSMOS field, to extend the search of highly obscured, Compton-thick active…

The all-sky hard X-ray survey performed by Swift/BAT allowed the detection of many heavily obscured Compton-thick AGN. In our previous work, we have identified more than 50 candidate Compton-thick AGN in the local Universe, corresponding to…

Astrophysics of Galaxies · Physics 2019-01-09 I. Georgantopoulos , A. Akylas

We present the most up-to-date X-ray luminosity function (XLF) and absorption function of Active Galactic Nuclei (AGNs) over the redshift range from 0 to 5, utilizing the largest, highly complete sample ever available obtained from surveys…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-18 Yoshihiro Ueda , Masayuki Akiyama , Guenther Hasinger , Takamitsu Miyaji , Michael G. Watson

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…

High Energy Astrophysical Phenomena · Physics 2017-01-11 Johannes Buchner , Franz E. Bauer

Kilo-parsec scale hard ($>$ 3 keV) X-ray continuum and fluorescent Fe K$\alpha$ line emission has been recently discovered in nearby Compton-thick (CT) active galactic nuclei (AGN), which opens new opportunities to improve AGN torus…

High Energy Astrophysical Phenomena · Physics 2023-05-17 Jingzhe Ma , Martin Elvis , G. Fabbiano , Mislav Balokovic , W. Peter Maksym , Guido Risaliti

This work discusses the broadband X-ray spectral analysis of 11 candidate heavily-obscured active galactic nuclei (AGN) selected based on their infrared and X-ray properties by a recently published machine learning algorithm. This paper is…