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arXiv 0712.3047astro-ph
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亚毫米星系的高分辨率射电观测

High-resolution radio observations of submillimetre galaxies

A. D. Biggs, R. J. Ivison

摘要:

我们已经产生了敏感的,高分辨率的无线电地图的12 SMG在洛克曼洞使用组合MERLIN和VLA数据在1.4 GHz的频率。积分350小时得到r.m.s.噪声为6.0 μ J/束,分辨率为0.2-0.5”。这是第一次,宽场数据从两个阵列已被合并在(u,v)平面和带宽拖影响应的VLA数据已被删除。在我们的地图中检测到所有SMG以及包括非亚毫米发光对照样品的源。我们发现的证据表明,SMG更扩展比一般uJy无线电人口,因此,与当地ULIRGs,星暴组成部分的无线电辐射的扩展,而不是局限于银河系的核心。对于八个源的红移,我们测量的线性尺寸在1和8千秒差距之间,中位数为5千秒差距。因此,它们通常比本地ULIRG大,这可能支持星爆触发的早期合并场景。在合并样本的33个来源中,有6个来源的X射线泄露了活动星系核。除了一个之外,所有这些都在控制样本中,这表明在亚毫米发光星系中AGN的发生率较低,这反过来又与这些尘埃遮蔽的星爆中X射线吸收增加相一致。只有一个源被解析为多个不同的组件与我们的高分辨率数据。最后,与以前对GOODS-N场中微弱射电源的研究相比,我们发现系统性的较小的源尺寸,并且没有证据表明尾部延伸到~4”。可能的原因进行了讨论。

英文摘要:

We have produced sensitive, high-resolution radio maps of 12 SMGs in the Lockman Hole using combined MERLIN and VLA data at a frequency of 1.4 GHz. Integrating for 350hr yielded an r.m.s. noise of 6.0 uJy/beam and a resolution of 0.2-0.5". For the first time, wide-field data from the two arrays have been combined in the (u,v) plane and the bandwidth smearing response of the VLA data has been removed. All of the SMGs are detected in our maps as well as sources comprising a non-submm luminous control sample. We find evidence that SMGs are more extended than the general uJy radio population and that therefore, unlike in local ULIRGs, the starburst component of the radio emission is extended and not confined to the galactic nucleus. For the eight sources with redshifts we measure linear sizes between 1 and 8 kpc with a median of 5 kpc. Therefore, they are in general larger than local ULIRGs which may support an early-stage merger scenario for the starburst trigger. X-rays betray AGN in six of the 33 sources in the combined sample. All but one of these are in the control sample, suggesting a lower incidence of AGN amongst the submm-luminous galaxies which is, in turn, consistent with increased X-ray absorption in these dust-obscured starbursts. Only one of our sources is resolved into multiple, distinct components with our high-resolution data. Finally, compared to a previous study of faint radio sources in the GOODS-N field we find systematically smaller source sizes and no evidence for a tail extending to ~4". Possible reasons for this are discussed.

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