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BASS. XXIII. A New Mid-infrared Diagnostic for Absorption in Active Galactic Nuclei

Pfeifle, Ryan W. and Ricci, Claudio and Boorman, Peter G. and Stalevski, Marko and Asmus, Daniel and Trakhtenbrot, Benny and Koss, Michael J. and Stern, Daniel and Ricci, Federica and Satyapal, Shobita and Ichikawa, Kohei and Rosario, David J. and Caglar, Turgay and Treister, Ezequiel and Powell, Meredith and Oh, Kyuseok and Urry, C. Megan and Harrison, Fiona (2022) BASS. XXIII. A New Mid-infrared Diagnostic for Absorption in Active Galactic Nuclei. Astrophysical Journal Supplement Series, 261 (1). Art. No. 3. ISSN 0067-0049. doi:10.3847/1538-4365/ac5b65.

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In this study, we use the Swift/BAT AGN sample, which has received extensive multiwavelength follow-up analysis as a result of the BAT AGN Spectroscopic Survey, to develop a diagnostic for nuclear obscuration by examining the relationship between the line-of-sight column densities (N_H), the 2–10 keV to 12 μm luminosity ratio, and WISE mid-infrared colors. We demonstrate that heavily obscured AGNs tend to exhibit both preferentially “redder” mid-infrared colors and lower values of L_(X,Obs.)/L_(12 μm) than less obscured AGNs, and we derive expressions relating N_H to the L_(X,Obs.)/L_(12 μm) and L_(22 μm)/L_(4.6 μm) luminosity ratios, as well as develop diagnostic criteria using these ratios. Our diagnostic regions yield samples that are ≳ 80% complete and ≳ 60% pure for AGNs with log(N_H/cm⁻²) ≥ 24, as well as ≳ 85% pure for AGNs with log(N_H/cm⁻²) ≳ 23.5. We find that these diagnostics cannot be used to differentiate between optically star-forming galaxies and active galaxies. Further, mid-IR contributions from host galaxies that dominate the observed 12 μm emission can lead to larger apparent X-ray deficits and redder mid-IR colors than the AGNs would intrinsically exhibit, though this effect helps to better separate less and more obscured AGNs. Finally, we test our diagnostics on two catalogs of AGNs and infrared galaxies, including the XMM-Newton XXL-N field, and we identify several known Compton-thick AGNs, as well as a handful of candidate heavily obscured AGNs based upon our proposed obscuration diagnostics.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Pfeifle, Ryan W.0000-0001-8640-8522
Ricci, Claudio0000-0001-5231-2645
Boorman, Peter G.0000-0001-9379-4716
Stalevski, Marko0000-0001-5146-8330
Asmus, Daniel0000-0003-0220-2063
Trakhtenbrot, Benny0000-0002-3683-7297
Koss, Michael J.0000-0002-7998-9581
Stern, Daniel0000-0003-2686-9241
Ricci, Federica0000-0001-5742-5980
Satyapal, Shobita0000-0003-2277-2354
Ichikawa, Kohei0000-0002-4377-903X
Rosario, David J.0000-0002-0001-3587
Caglar, Turgay0000-0002-9144-2255
Treister, Ezequiel0000-0001-7568-6412
Powell, Meredith0000-0003-2284-8603
Oh, Kyuseok0000-0002-5037-951X
Urry, C. Megan0000-0002-0745-9792
Harrison, Fiona0000-0003-2992-8024
Alternate Title:BAT AGN Spectroscopic Survey-XXIII. A New Mid-Infrared Diagnostic for Absorption in Active Galactic Nuclei
Additional Information:© 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Received 2020 August 12; revised 2021 January 25; accepted 2021 February 5; published 2022 July 15. The BAT AGN Spectroscopic Survey Data Release 2. We graciously thank the anonymous referee whose timely and constructive feedback aided in improving this work. We thank L. Shao and R. Boissay-Malaquin for their helpful comments on the draft. R.W.P. thanks B. L. Cale for helpful discussions regarding data fitting with Python. C.R. acknowledges support from the Fondecyt Iniciacion grant 11190831 and ANID BASAL project FB210003. P.G.B. acknowledges financial support from the STFC and Czech Science Foundation project No. 19-05599Y. D.A. acknowledges funding through the European Union's Horizon 2020 innovation program under Marie Sklodowska-Curie grant agreement No. 793499 (DUSTDEVILS). B.T. acknowledges support from the Israel Science Foundation (grant 1849/19) and from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (grant agreement 950533). M.K. acknowledges support from NASA through ADAP award NNH16CT03C. F.R. acknowledges support from FONDECYT postdoctorado 3180506. E.T. acknowledges support from FONDECYT Regular 1190818 and 1200495, ANID grants CATA-Basal AFB-170002, ACE210002, and FB210003, and Millennium Nucleus NCN19_058. This work is partially supported by the Japan Society for the Promotion of Science (JSPS) KAKENHI (18K13584 and 20H01939; K.I.). K.O. acknowledges support from the National Research Foundation of Korea (NRF-2020R1C1C1005462). M.S. acknowledges support by the Ministry of Education, Science and Technological Development of the Republic of Serbia through contract No. 451-03-68/2020/14/20002 and the Science Fund of the Republic of Serbia, PROMIS 6060916, BOWIE. Facilities: Chandra, GALEX, NuSTAR, SDSS, Suzaku, Swift, WISE, XMM-Newton. Software: odr (Boggs & Rogers et al. 1990; Virtanen et al. 2020), pandas (McKinney 2010), scipy (Virtanen et al. 2020), numpy (Oliphant 2006; van der Walt et al. 2011; Oliphant 2015), matplotlib (Hunter 2007), BXA (Buchner et al. 2014). This publication makes use of data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration. Funding for SDSS-III has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, and the U.S. Department of Energy Office of Science. The SDSS-III website is 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.
Group:Astronomy Department, Space Radiation Laboratory
Funding AgencyGrant Number
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)11190831
Agencia Nacional de Investigación y Desarrollo (ANID)FB210003
Science and Technology Facilities Council (STFC)UNSPECIFIED
Czech Science Foundation19-05599Y
Marie Curie Fellowship793499
Israel Science Foundation1849/19
European Research Council (ERC)950533
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)3180506
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1190818
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1200495
Agencia Nacional de Investigación y Desarrollo (ANID)ACE210002
Agencia Nacional de Investigación y Desarrollo (ANID)FB210003
Agencia Nacional de Investigación y Desarrollo (ANID)NCN19_058
Japan Society for the Promotion of Science (JSPS)18K13584
Japan Society for the Promotion of Science (JSPS)20H01939
National Research Foundation of KoreaNRF-2020R1C1C1005462
Ministry of Education, Science and Technological Development (Serbia)451-03-68/2020/14/20002
Science Fund (Serbia)6060916
Alfred P. Sloan FoundationUNSPECIFIED
Participating InstitutionsUNSPECIFIED
Department of Energy (DOE)UNSPECIFIED
Subject Keywords:Supermassive black holes; Active galactic nuclei; Black hole physics; X-ray active galactic nuclei; AGN host galaxies
Issue or Number:1
Classification Code:Unified Astronomy Thesaurus concepts: Supermassive black holes (1663); Active galactic nuclei (16); Black hole physics (159); X-ray active galactic nuclei (2035); AGN host galaxies (2017)
Record Number:CaltechAUTHORS:20220727-37302000
Persistent URL:
Official Citation:Ryan W. Pfeifle et al 2022 ApJS 261 3
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:115906
Deposited By: George Porter
Deposited On:29 Jul 2022 16:02
Last Modified:03 Aug 2022 21:07

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