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arXiv 1104.4882astro-ph.COastro-ph.GA
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NGC6240的VLBI观测:解析双核和射电超新星

VLBI Observations of NGC6240: resolving the double nuclei and radio supernovae

Y. Hagiwara, W. A. Baan, H. -R. Kloeckner

摘要:

欧洲VLBI网络(EVN)在2003年和2009年的两个时期获得了合并星系NGC 6240的多频高分辨率图像,以研究星系中所有紧凑的高亮度组件的射电特性。我们在毫弧秒分辨率的观测发现了北核和南核以及两个射电成分,我们将其解释为与南核环核星暴活动相关的长寿命发光超新星。新的VLBI数据支持南核存在活动星系核和星暴活动,并为北核存在活动星系核提供了一些证据。这两个原子核在较低的GHz频率下都显示出倒置的光谱。南核的光谱表明在秒差距尺度上的热自由-自由吸收,与活动星系核的存在相一致。

英文摘要:

The European VLBI Network (EVN) has been used at two epochs in 2003 and 2009 to obtain multi-frequency high-resolution images of the merger galaxy NGC6240 in order to study the radio properties of all compact high-brightness components in the galaxy. Our observations at milli-arcsecond resolution detected the northern and southern nuclei and two radio components, which we interpret as long-lived luminous supernovae associated with the circum-nuclear starburst activity at the southern nucleus. The new VLBI data support the presence of an active galactic nucleus (AGN) together with starburst activity at the southern nucleus and provides some evidence for an AGN at the northern nucleus. The two nuclei both display an inverted spectrum at lower GHz frequencies. The spectrum of the southern nucleus indicates thermal free-free absorption on parsec scales, consistent with the presence of an AGN.

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