BAT AGN Spectroscopic Survey. XI. The Covering Factor of Dust and Gas in Swift/BAT Active Galactic Nuclei
BAT AGN Spectroscopic Survey. XI. The Covering Factor of Dust and Gas in Swift/BAT Active Galactic Nuclei
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DOI：
10.3847/1538-4357/aaef8f
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发表时间：
2018-11
期刊：
影响因子：
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通讯作者：
K. Ichikawa;C. Ricci;Y. Ueda;F. Bauer;T. Kawamuro;M. Koss;K. Oh;D. Rosario;T. Shimizu
中科院分区：
文献类型：
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作者：
K. Ichikawa;C. Ricci;Y. Ueda;F. Bauer;T. Kawamuro;M. Koss;K. Oh;D. Rosario;T. Shimizu
利用雨燕/爆发警报望远镜（BAT）70个月全天超硬X射线巡天观测资料，定量分析了活动星系核（AGN）对局部AGN 12 μm、中红外（MIR; 5-38 μm）和总红外（5-1000 μm）辐射的贡献。我们分解的587个对象的红外光谱能量分布（SED）到AGN和星爆组件使用AGN环和恒星形成星系的模板。这使我们能够恢复从活动星系核环面的发射，包括低光度端，下至，这通常有显着的宿主星系污染。样品表明活动星系核对12 μm波段、MIR波段和总IR波段的光度贡献是14-150 keV光度的增函数。我们还发现，在最极端的情况下，红外纯活动星系核的辐射可以延伸到90 μm。通过IR SED分解获得的总IR AGN光度使我们能够估计被尘埃遮蔽的天空部分，即，灰尘覆盖系数。我们证明，中值尘埃覆盖因子总是小于中值X射线遮蔽分数以上的活动星系核的热光度。考虑到X射线遮蔽率等于尘埃和气体的覆盖因子，这表明沿着尘埃环的额外中性气体成分负责X射线发射的吸收。
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 , 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 . 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.