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The goal of this work is to study the obscuration properties of mid-infrared (mid-IR) selected AGN. For that purpose, we use {\it{WISE}} sources in the Stripe 82-XMM area to identify mid-IR AGN candidates, applying the Assef et al.…

Astrophysics of Galaxies · Physics 2020-01-08 G. Mountrichas , I. Georgantopoulos , A. Ruiz , G. Kampylis

We present a highly complete and reliable mid-infrared (MIR) colour selection of luminous AGN candidates using the 3.4, 4.6, and 12 um bands of the WISE survey. The MIR colour wedge was defined using the wide-angle Bright Ultra-Hard…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 S. Mateos , A. Alonso-Herrero , F. J. Carrera , A. Blain , M. G. Watson , X. Barcons , V. Braito , P. Severgnini , J. L. Donley , D. Stern

(abridged) We identify a numerically significant population of heavily obscured AGNs at z~0.5-1 in the Chandra Deep Field-South (CDF-S) and Extended Chandra Deep Field-South by selecting 242 X-ray undetected objects with infrared-based star…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 B. Luo , W. N. Brandt , Y. Q. Xue , D. M. Alexander , M. Brusa , F. E. Bauer , A. Comastri , A. C. Fabian , R. Gilli , B. D. Lehmer , D. A. Rafferty , D. P. Schneider , C. Vignali

(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

We present a comprehensive analysis of the X-ray spectral properties of 198 newly identified active galactic nuclei (AGNs), leveraging archival data from the {\it Chandra} X-ray Observatory. All these AGNs exhibit a powerlaw spectral…

High Energy Astrophysical Phenomena · Physics 2024-10-08 Samrat Ghosh , Samir Mandal , Sudip Bhattacharyya , Shivam Kumaran

We present XMM-Newton observations of three AGN taken as part of a hunt to find very heavily obscured Compton-thick AGN. For obscuring columns greater than 10^25 cm^-2, AGN are only visible at energies below 10 keV via reflected/scattered…

High Energy Astrophysical Phenomena · Physics 2015-05-28 M. L. Trippe , C. S. Reynolds , M. Koss , R. F. Mushotzky , L. M. Winter

Using the large multi-wavelength data set in the chandra/SWIRE Survey (0.6 square degrees in the Lockman Hole), we show evidence for the existence of highly obscured (Compton-thick) AGN, estimate a lower limit to their surface density and…

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

We introduce a new infrared diagnostic to separate galaxies on the basis of their dominant infrared emission: stellar or nuclear. The main novelty with respect to existing diagnostics, is the usage of a broad band encompassing at the same…

Astrophysics of Galaxies · Physics 2015-06-22 Dario Fadda , Giulia Rodighiero

The active galactic nuclei X-ray luminosity function traces actively accreting supermassive black holes and is essential for the study of the properties of the active galactic nuclei (AGN) population, black hole evolution, and galaxy-black…

Through an optical campaign performed at the San Pedro Martir (Mexico) Telescope and using the 6dF archive (http://www.aao.gov.au/local/www/6df, Jones et al. 2004), we determine or give a better classification for 8 newly discovered Active…

Cosmology and Nongalactic Astrophysics · Physics 2019-08-14 Pietro Parisi

We present a detailed analysis of the most luminous and obscured Active Galactic Nuclei (AGNs) detected in the ultra-hard X-ray band (14-195 keV) by Swift/BAT. Our sample comprises 21 X-ray luminous (log $L_X/{\rm erg\,s^{-1}}>44.6$, 2-10…

Spitzer IRAC selection is a powerful tool for identifying luminous AGN. For deep IRAC data, however, the AGN selection wedges currently in use are heavily contaminated by star-forming galaxies, especially at high redshift. Using the large…

We investigate the far-infrared (far-IR) incidence of X-ray-selected active galactic nuclei (AGN) and non-AGN galaxies as a function of stellar mass (M$_*$), star formation rate (SFR), and specific black hole accretion rate…

Astrophysics of Galaxies · Physics 2025-08-27 G. Mountrichas , F. J. Carrera , I. Georgantopoulos , S. Mateos , A. Ruiz , A. Corral

[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

In this paper we study the nuclear obscuration of galaxies hosting LINERs based on their X-ray and optical emission. They show column densities (N_H) at soft energies (0.5-2 keV) mostly related to the diffuse emission around the AGN,…

Astrophysics of Galaxies · Physics 2014-11-20 O. Gonzalez-Martin , J. Masegosa , I. Marquez , M. Guainazzi

We present the analysis of a sample of 35 candidate Compton thick (CT-) active galactic nuclei (AGNs) selected in the nearby Universe (average redshift <z>~0.03) with the Swift-BAT 100-month survey. All sources have available NuSTAR data,…

The 500ks Chandra ACIS-I observation of the field around the $z=6.31$ quasar SDSS J1030+0524 is currently the 5th deepest extragalactic X-ray survey. The rich multi-band coverage of the field allowed for an effective identification and…

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…

Astrophysics · Physics 2009-11-13 L. C. Gallo , I. Lehmann , W. Pietsch , Th. Boller , W. Brinkmann , P. Friedrich , D. Grupe

We report the results obtained by a systematic, broadband (0.5--150 keV) X-ray spectral analysis of moderately obscured (Compton-thin; $22 \leq \log N_{\rm H} < 24$) active galactic nuclei (AGNs) observed with Suzaku and Swift/Burst Alert…

High Energy Astrophysical Phenomena · Physics 2016-08-03 Taiki Kawamuro , Yoshihiro Ueda , Fumie Tazaki , Claudio Ricci , Yuichi Terashima