论文标题
将X射线和21厘米HI吸收气柱密度降低到被遮盖的AGN
Reconciling X-ray and 21cm HI absorption gas column densities toward obscured AGN
论文作者
论文摘要
从X射线吸收推断出的氢柱密度通常比中性原子氢柱密度高5-30倍，该密度从21cm HI吸收衍生而来，向无线电大 - 大声的活性银河核。差异的某些部分归因于自旋温度\ tsp \ = 100 K的不确定性，该\ = 100 K通常用于将21cm HI HI吸收转换为N（HI）。在这里，我们提出了另一种方法来从HI吸收中推断气柱。在我们的银河系中，整体测量的21厘米hi吸收\ whi \ and Reddening，\ whi \ $ \ propto $ \ ebv $^{1.10} $之间的整体测量21cm HI吸收\ whi \ whi \ whi \ whi \ apv $ \ $ \ ga 0.7 $ \ ga 0.7 $ \ kmms \ agv agv ga，然后，从同一灰尘柱中提供了总体气柱密度n（h），该灰尘柱负责光学遮挡和X射线吸收，而无需计算n（hi）。 n（h）的值通常超过n（hi），因为无处不在的银河系21cm HI HI吸收样品仅部分星际气体。如果研究良好的Hydra-A病例是一个指南，则可以通过解决21cm HI吸收的N（H）来解释X射线和21厘米HI气柱密度的很大差异。在讨论被模糊的AGN的讨论中，经常会引用银河系条件，因此以银河系方式看到的经验关系应该是相关的基准。
Hydrogen column densities inferred from X-ray absorption are typically 5 - 30 times larger than the neutral atomic hydrogen column densities derived from 21cm HI absorption toward radio-loud active galactic nuclei. Some part of the difference is ascribed to uncertainty in the spin temperature \Tsp\ = 100 K that is often used to convert 21cm HI HI absorption to N(HI). Here we propose another way to infer the gas column from HI absorption. In our Galaxy there is a nearly linear correlation between the inteferometrically-measured integrated 21cm HI absorption \WHI\ and reddening, \WHI\ $\propto$ \EBV$^{1.10}$ for \WHI\ $\ga 0.7$ \kms\ or \EBV\ $\ga 0.04$ mag. Scaling \EBV\ then provides the total gas column density N(H) from the same dust column that is responsible for optical obscuration and X-ray absorption, without calculating N(HI). Values of N(H) so derived typically exceed N(HI) by a factor 4 because the ubiquitous Galactic 21cm HI HI absorption samples only a portion of the interstellar gas. If the well-studied case of Hydra-A is a guide, even very large disparities in X-ray and 21cm HI gas column densities can be explained by resolving the core radiocontinuum and inferring N(H) from 21cm HI absorption. Milky Way conditions are often invoked in discussion of obscured AGN, so the empirical relationship seen in the Milky Way should be a relevant benchmark.
