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arXiv 1107.5155astro-ph.CO
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窄线Seyfert 1星系:一个聚集类AGN

Narrow-line Seyfert 1 galaxies: an amasing class of AGN

A. Tarchi, P. Castangia, A. Columbano, F. Panessa, J. A. Braatz

摘要:

窄线塞弗特1(NLS 1)星系是一类活动星系核(AGN),具有1型塞弗特星系的所有特性,但显示出独特的特征,包括最窄的巴耳末线,最强的Fe II发射和极端的X射线特性。线和连续射电观测提供了一个最佳的工具,以访问(往往)光学模糊的AGN的最里面的区域,并揭示其中央发动机周围的气体的运动学。我们研究了活动星系核特有的NLS 1类与脉泽现象之间的相互作用,以帮助我们理解某些NLS 1类中已探测到水脉泽发射的脉泽发射的性质。我们观察了一个样本的NLS 1星系的绿岸望远镜在寻找水脉泽发射在22 GHz。我们还减少和分析档案绿岸望远镜和甚大阵列数据,并产生22 GHz的光谱与检测到的脉泽发射的五个NLS 1星系。特别地,我们用甚大阵在亚角秒尺度上对NGC 5506的脉泽和核射电连续谱进行了成像。我们在两个NLS 1星系IGRJ 16385 -2057和IRAS 03450 +0055中发现了脉泽发射。除了在NLS 1 s Mrk 766、NGC 4051和NGC 5506中的三个已知的脉泽探测之外,这产生了NLS 1星系中的水脉泽探测率约为7%(5/71)。当只考虑退行速度小于10000 km/s的NLS 1星系时,这个值显着上升到~21%(5/24)。对于NGC 4051和NGC 5506,我们发现水脉泽发射分别位于核射电连续结的5和12 pc范围内,这被解释为核心喷流结构。

英文摘要:

[Abridged] Narrow-line Seyfert 1 (NLS1) galaxies are a class of active galactic nuclei (AGN) that have all the properties of type 1 Seyfert galaxies but show peculiar characteristics, including the narrowest Balmer lines, strongest Fe II emission, and extreme properties in the X-rays. Line and continuum radio observations provide an optimal tool to access the (often) optically obscured innermost regions of AGN and reveal the kinematics of the gas around their central engines. We investigate the interplay between the peculiar NLS1 class of AGN and the maser phenomenon, to help us understand the nature of the maser emission in some NLS1s where water maser emission has been detected. We observed a sample of NLS1 galaxies with the Green Bank Telescope in a search for water maser emission at 22 GHz. We also reduced and analysed archival Green Bank Telescope and Very Large Array data and produced 22-GHz spectra for the five NLS1 galaxies with detected maser emission. In particular, we imaged the maser and nuclear radio continuum of NGC5506 at subarcsec scales with the Very Large Array. We discovered maser emission in two NLS1 galaxies: IGRJ16385-2057, and IRAS03450+0055. In addition to the three previously known maser detections in the NLS1s Mrk766, NGC4051, and NGC5506, this yields a water maser detection rate in NLS1 galaxies of ~7% (5/71). This value rises significantly to ~21% (5/24) when considering only NLS1 galaxies at recessional velocities less than 10000 km/s. For NGC4051 and NGC5506, we find that the water maser emission is located within 5 and 12 pc, respectively, of nuclear radio continuum knots, which are interpreted as core-jet structures.

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