Powerful Water Masers in Active Galactic Nuclei
Powerful Water Masers in Active Galactic Nuclei
复制标题
活跃星系核中强大的水脉泽
DOI：
10.1071/as01100
复制
发表时间：
2002
影响因子：
6.3
通讯作者：
P. Maloney
中科院分区：
文献类型：
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作者：
P. Maloney
在20多个星系中探测到了22 GHz的616-523线的水脉泽发光。在所有的情况下，辐射都局限在核内，并且只在活动星系核中发现，特别是在2型塞弗特和LINER中。我认为，大多数观察到的超脉泽源是由X射线辐射的致密气体的中央引擎。在简要回顾了这些X射线离解区域的物理学之后，我详细讨论了NGC 4258中脉泽盘的观测结果，它的含义，并比较了脉泽发射的替代模型。然后，我讨论的其他来源，已与VLBI成像的日期，以及他们如何做或不适合一个薄的，旋转盘的框架，如在NGC 4258。最后，我简要地讨论了未来的前景，特别是探测其他水脉泽跃迁的可能性。
Abstract Luminous water maser emission in the 616–523 line at 22GHz has been detected from two dozen galaxies. In all cases the emission is confined to the nucleus and has been found only in AGN, in particular, in Type 2 Seyferts and LINERs. I argue that most of the observed megamaser sources are powered by X-ray irradiation of dense gas by the central engine. After briefly reviewing the physics of these X-Ray Dissociation Regions, I discuss in detail the observations of the maser disk in NGC 4258, its implications, and compare alternative models for the maser emission. I then discuss the observations of the other sources that have been imaged with VLBI to date, and how they do or do not fit into the framework of a thin, rotating disk, as in NGC 4258. Finally, I briefly discuss future prospects, especially the possibility of detecting other water maser transitions.