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河外H2O超脉泽辐射
徐 烨
1,2 蒋栋荣 1,2 郑兴武 3
俞志尧 1,2
(1.
中国科学院上海天文台 上海 200030)
(2. 中国科学院国家天文台 北京 100012)
(3. 南京大学天文系 南京 210008)
摘 要
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介绍了近年来河外H2O超脉泽的主要观测结果。H2O超脉泽通常起源于活动星系核中央的拱核盘。它们主要寄生在Serfert
2星系或低电离核区。至今为止，已有20个星系探测到H2O超脉泽。脉泽辐射的各向同性光度为10－6000L¤。所有超脉泽星系显示出核的活动，显然，脉泽是由核活动所产生的射电和X射线光子或激波来抽运的。H2O超脉泽倾向存在于高倾斜度的星系，这使得沿视线上的分子柱密度增高，产生足够大的放大光深。最有可能产生H2O超脉泽辐射的星系应有一个包含着射电源的侧向的分子盘以及一个适当的抽运机制。
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H2O
Megamasers in Extragalaxies
Xu
Ye 1,2 Jiang
Dongrong 1,2
Zheng Xingwu 3 Yu Zhiyao 1,2
(1. Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai
200030)
(2. National Astronomical Observatories, Chinese Academy of Sciences, Beijing
100080)
(3. Department of Astronomy, Nanjing University, Nanjing 210093)
Abstract
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Main observational results and theoretical studies for H2O
Megamasers are briefly reviewed. The H2O Megamaser emission
often originates in thin circumnuclear disks near the centers of
active galactic nuclei (AGN) and has been detected in 20 galaxies with
isotropic luminosities of about 10－6000L¤.
All of megamaser galaxies show evidence for nuclear activity, being
classified as either Seyfert 2 or LINER, so there appears to be a link
between the megamaser phenomenon and AGN. There was a trend for
megamasers to occur preferentially in highly inclined host galaxies.
The AGN apparently produces the seed radio photons and the X-ray
photons or shock waves need to pump the maser material. The observed
spectral characteristics support a model with inverted molecular gas
located in front of the nuclear source that in part amplifies the
background continuum.
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