Measurement of AGN dust extinction based on the near-infrared flux variability of <i>WISE</i> data
Measurement of AGN dust extinction based on the near-infrared flux variability of <i>WISE</i> data
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基于<i>WISE</i>数据的近红外通量变化测量AGN尘埃消光
DOI：
10.1093/mnras/stac2307
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发表时间：
2022
影响因子：
4.8
通讯作者：
Noda Hirofumi
中科院分区：
文献类型：
--
作者：
Mizukoshi Shoichiro;Minezaki Takeo;Tsunetsugu Shoichi;Yoshida Atsuhiro;Sameshima Hiroaki;Kokubo Mitsuru;Noda Hirofumi
我们基于近红外（NIR）波长中可变通量分量颜色的变红，提出了对大量模糊活动星系核（AGN）的尘埃环面视线消光的测量。我们通过广域红外巡天探测器 (WISE) 收集了 Swift/BAT AGN 光谱巡天 (BASS) 编目的 513 个本地 AGN 的长期监测数据，发现两个不同波段（WISE W1 和 W2）的多历元 NIR 通量数据与 90% 以上的目标紧密相关。 W1和W2波段的通量变化梯度（FVG）是通过应用线性回归分析得出的，我们报告说，未被遮挡的活动星系核的通量变化梯度落在相对较窄的范围内，而被遮挡的活动星系核的通量变化梯度则分布在更红和更宽的范围内。 AGN 的视线消光 (AV) 是使用 FVG 中的红化量计算的，并与 BASS 目录中的中性氢柱密度 (NH) 进行比较。我们发现，被遮挡的活动星系核的NH/AV比值大于银河系弥漫星际介质（ISM）的NH/AV比值，并且其分布具有较大的分散度，最多两个数量级。此外，我们发现被遮挡的 AGN 的 NH/AV 的下包络线与银河系弥漫的 ISM 相当。 NH/AV 的这些特性可以通过 NH 的增加来解释，归因于覆盖宽线区域视线的无尘气体云。
We present the measurement of the line-of-sight extinction of the dusty torus for a large number of obscured active galactic nuclei (AGNs) based on the reddening of the colour of the variable flux component in near-infrared (NIR) wavelengths. We collected long-term monitoring data by Wide-field Infrared Survey Explorer (WISE) for 513 local AGNs catalogued by theSwift/BAT AGN Spectroscopic Survey (BASS) and found that the multi-epoch NIR flux data in two different bands (WISE W1 andW2) are tightly correlated for more than 90 per cent of the targets. The flux variation gradient (FVG) in theW1 andW2 bands was derived by applying linear regression analysis, and we reported that those for unobscured AGNs fall in a relatively narrow range, whereas those for obscured AGNs are distributed in a redder and broader range. The AGN’s line-of-sight dust extinction (AV) is calculated using the amount of the reddening in the FVG and is compared with the neutral hydrogen column density (NH) of the BASS catalogue. We found that theNH/AVratios of obscured AGNs are greater than those of the Galactic diffuse interstellar medium (ISM) and are distributed with a large scatter by at most two orders of magnitude. Furthermore, we found that the lower envelope of theNH/AVof obscured AGNs is comparable to the Galactic diffuse ISM. These properties of theNH/AVcan be explained by increase in theNHattributed to the dust-free gas clouds covering the line of sight in the broad-line region.