TY - JOUR
T1 - BAT AGN Spectroscopic Survey. XI. the Covering Factor of Dust and Gas in Swift/BAT Active Galactic Nuclei
AU - Ichikawa, Kohei
AU - Ricci, Claudio
AU - Ueda, Yoshihiro
AU - Bauer, Franz E.
AU - Kawamuro, Taiki
AU - Koss, Michael J.
AU - Oh, Kyuseok
AU - Rosario, David J.
AU - Shimizu, T. Taro
AU - Stalevski, Marko
AU - Fuller, Lindsay
AU - Packham, Christopher
AU - Trakhtenbrot, Benny
N1 - Funding Information:
We thank the anonymous referee for a careful reading of the manuscript and helpful suggestions that greatly strengthened the paper. We thank James Mullaney and Agnese Del Moro for providing the SB SED templates in this study, and Satoshi Takeshige for the technical discussion of IDL routine. We also thank Masatoshi Imanishi, Ryo Tazaki, and Daniel Asmus for fruitful discussions. K.I. thanks the Department of Astronomy at Kyoto university, where a part of the research was conducted. This study benefited from financial support from the Grant-in-Aid for JSPS fellow for young researchers (P.D., K.I.), JSPS KAKENHI (18K13584; K.I.), and JST grant “Building of Consortia for the Development of Human Resources in Science and Technology” (K.I.). C.R. acknowledges the CONICYT+PAI Convocatoria Nacional subvencion a instalacion en la academia convocatoria año 2017 PAI77170080. F.E.B. acknowledges support from CONI-CYT-Chile (Basal-CATA PFB-06/2007, FONDECYT Regular 1141218), the Ministry of Economy, Development, and Tourism’s Millennium Science Initiative through grant IC120009, awarded to The Millennium Institute of Astrophysics, MAS. K.O. is an International Research Fellow of the Japan Society for the Promotion of Science (JSPS) (ID: P17321). D.J.R. acknowledges the support of UK Science and Technology Facilities Council through grant code ST/ P000541/1.
Publisher Copyright:
© 2019. The American Astronomical Society. All rights reserved.
PY - 2019/1/1
Y1 - 2019/1/1
N2 - We quantify the luminosity contribution of active galactic nuclei (AGNs) to the 12 μm, mid-infrared (MIR; 5-38 μm), and total IR (5-1000 μm) emission in the local AGNs detected in the all-sky 70 month Swift/Burst Alert Telescope (BAT) ultrahard X-ray survey. We decompose the IR spectral energy distributions (SEDs) of 587 objects into the AGN and starburst components using templates for an AGN torus and a star-forming galaxy. This enables us to recover the emission from the AGN torus including the low-luminosity end, down to log(L14-50/erg s-1) ≃ 41, which typically has significant host galaxy contamination. The sample demonstrates that the luminosity contribution of the AGN to the 12 μm, the MIR, and the total IR bands is an increasing function of the 14-150 keV luminosity. We also find that for the most extreme cases, the IR pure-AGN emission from the torus can extend up to 90 μm. The total IR AGN luminosity obtained through the IR SED decomposition enables us to estimate the fraction of the sky obscured by dust, i.e., the dust covering factor. We demonstrate that the median dust covering factor is always smaller than the median X-ray obscuration fraction above an AGN bolometric luminosity of log(L(AGN) bol/erg s-1) ≃ 42.5. Considering that the X-ray obscuration fraction is equivalent to the covering factor coming from both the dust and gas, this indicates that an additional neutral gas component, along with the dusty torus, is responsible for the absorption of X-ray emission.
AB - We quantify the luminosity contribution of active galactic nuclei (AGNs) to the 12 μm, mid-infrared (MIR; 5-38 μm), and total IR (5-1000 μm) emission in the local AGNs detected in the all-sky 70 month Swift/Burst Alert Telescope (BAT) ultrahard X-ray survey. We decompose the IR spectral energy distributions (SEDs) of 587 objects into the AGN and starburst components using templates for an AGN torus and a star-forming galaxy. This enables us to recover the emission from the AGN torus including the low-luminosity end, down to log(L14-50/erg s-1) ≃ 41, which typically has significant host galaxy contamination. The sample demonstrates that the luminosity contribution of the AGN to the 12 μm, the MIR, and the total IR bands is an increasing function of the 14-150 keV luminosity. We also find that for the most extreme cases, the IR pure-AGN emission from the torus can extend up to 90 μm. The total IR AGN luminosity obtained through the IR SED decomposition enables us to estimate the fraction of the sky obscured by dust, i.e., the dust covering factor. We demonstrate that the median dust covering factor is always smaller than the median X-ray obscuration fraction above an AGN bolometric luminosity of log(L(AGN) bol/erg s-1) ≃ 42.5. Considering that the X-ray obscuration fraction is equivalent to the covering factor coming from both the dust and gas, this indicates that an additional neutral gas component, along with the dusty torus, is responsible for the absorption of X-ray emission.
KW - galaxies: active
KW - galaxies: nuclei
KW - infrared: galaxies
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U2 - 10.3847/1538-4357/aaef8f
DO - 10.3847/1538-4357/aaef8f
M3 - Article
AN - SCOPUS:85059831042
SN - 0004-637X
VL - 870
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1
M1 - 31
ER -