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Physically motivated X-ray obscurer models

Buchner, Johannes and Brightman, Murray and Baloković, Mislav and Wada, Keiichi and Bauer, Franz E. and Nandra, Kirpal (2021) Physically motivated X-ray obscurer models. Astronomy and Astrophysics, 651 . Art. No. A58. ISSN 0004-6361. doi:10.1051/0004-6361/201834963.

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Context. The nuclear obscurer of active galactic nuclei (AGN) is poorly understood in terms of its origin, geometry, and dynamics. Aims. We investigate whether physically motivated geometries emerging from hydro-radiative simulations can be differentiated with X-ray reflection spectroscopy. Methods. For two new geometries, the radiative fountain model and a warped disk, we release spectral models produced with the ray tracing code XARS. We contrast these models with spectra of three nearby AGN taken by NuSTAR and Swift/BAT. Results. Along heavily obscured sightlines, the models present different 4−20 keV continuum spectra. These can be differentiated by current observations. Spectral fits of the Circinus Galaxy favour the warped disk model over the radiative fountain, and clumpy or smooth torus models. Conclusions. The necessary reflector (N_H ≥ 10²⁵ cm²) suggests a hidden population of heavily Compton-thick AGN amongst local galaxies. X-ray reflection spectroscopy is a promising pathway to understand the nuclear obscurer in AGN.

Item Type:Article
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URLURL TypeDescription Paper
Buchner, Johannes0000-0003-0426-6634
Brightman, Murray0000-0002-8147-2602
Baloković, Mislav0000-0003-0476-6647
Bauer, Franz E.0000-0002-8686-8737
Nandra, Kirpal0000-0002-7150-9192
Additional Information:© J. Buchner et al. 2021. Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Open Access funding provided by Max Planck Society. Received: 20 December 2018; Accepted: 1 June 2021. We thank the anonymous referees for constructive suggestions which improved the manuscript. We acknowledge support from the CONICYT-Chile grants Basal-CATA PFB-06/2007 (JB, FEB), ANID grants CATA-Basal AFB-170002 (JB, FEB), FONDECYT Regular 1141218, 1190818 and 1200495 (all FEB), FONDECYT Postdoctorados 3160439 (JB), “EMBIGGEN” Anillo ACT1101 (FEB), and the Ministry of Economy, Development, and Tourism’s Millennium Science Initiative through grant IC120009, awarded to The Millennium Institute of Astrophysics, MAS (JB, FEB). This research was supported by the DFG cluster of excellence “Origin and Structure of the Universe”. MiB acknowledges support from NASA Headquarters under the NASA Earth and Space Science Fellowship Program, the YCAA Prize Postdoctoral Fellowship, grant NNX14AQ07H, and support from the Black Hole Initiative at Harvard University, which is funded in part by the Gordon and Betty Moore Foundation (grant GBMF8273) and in part by the John Templeton Foundation. KW was supported by JSPS KAKENHI Grant Number 16H03959. This research has made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. This research has made use of SIMBAD (Wenger et al. 2000) and its excellent query API, operated by the Strasbourg astronomical Data Center (CDS).
Group:Space Radiation Laboratory
Funding AgencyGrant Number
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1141218
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1190818
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1200495
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)3160439
Comisión Nacional de Investigación Científica y Tecnológica (CONICYT)ACT1101
Iniciativa Científica Milenio del Ministerio de Economía, Fomento y TurismoIC120009
Deutsche Forschungsgemeinschaft (DFG)UNSPECIFIED
NASA Earth and Space Science FellowshipNNX14AQ07H
Gordon and Betty Moore FoundationGBMF8273
John Templeton FoundationUNSPECIFIED
Japan Society for the Promotion of Science (JSPS)16H03959
Subject Keywords:galaxies: active – accretion, accretion disks – methods: numerical – X-rays: general – radiative transfer – scattering
Record Number:CaltechAUTHORS:20210722-211238306
Persistent URL:
Official Citation:Physically motivated X-ray obscurer models. Johannes Buchner, Murray Brightman, Mislav Baloković, Keiichi Wada, Franz E. Bauer and Kirpal Nandra. A&A, 651 (2021) A58; DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:109983
Deposited By: Tony Diaz
Deposited On:26 Jul 2021 22:30
Last Modified:26 Jul 2021 22:30

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