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arXiv 0708.0158astro-ph
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为超亮红外星系IRAS 00182--7112提供能量的康普顿厚AGN

A Compton Thick AGN Powering the Hyperluminous Infrared Galaxy IRAS 00182--7112

K. Nandra, K. Iwasawa

摘要:

本文介绍了用XMM-Newton EPIC相机对超亮红外星系(HLIRG)IRAS 00182- 7112(F00183- 7111)的X射线观测结果。揭示了与原子核重合的发光硬X射线源,以及较弱的软X射线发射,该发射可能会从硬X射线中延伸或抵消。EPIC光谱是非常平坦的,并显示了Fe K $α$发射具有非常高的等效宽度:这两个都是一个埋,康普顿-厚AGN,这是看到只有在散射光的典型特征。也许该光谱最显著的特征是Fe K $α$线的能量是类He铁的能量,这使得IRAS 00182- 7112成为已知的第一个被电离的康普顿厚反射控制的隐藏活动星系核。采取适当的辐射热修正,我们发现,这个活动星系核可以很容易地主导FIR能量。核反射光谱是通过一个相对冷的吸收体看到的,其柱密度与斯皮策最近的观测结果一致。软X射线发射,可能是热的性质,并与恒星形成活动有关,被认为是未被吸收的。软X射线和弱PAH特征都给出了恒星形成速率$\sim 300 M_{\odot}$ yr $^{-1}$的估计,不足以为远红外辐射提供能量,也支持了这一HLIRG是活动星系核主导的观点。

英文摘要:

We present X-ray observations of the Hyperluminous Infrared Galaxy (HLIRG) IRAS 00182--7112 (F00183--7111) obtained using the XMM-Newton EPIC camera. A luminous hard X-ray source co-incident with the nucleus is revealed, along with weaker soft X-ray emission which may be extended or offset from the hard. The EPIC spectrum is extremely flat and shows Fe K$α$ emission with very high equivalent width: both are typical characteristics of a buried, Compton--thick AGN which is seen only in scattered light. Perhaps the most remarkable characteristic of the spectrum is that the Fe K$α$ line energy is that of He-like iron, making IRAS 00182--7112 the first hidden AGN known to be dominated by ionized, Compton thick reflection. Taking an appropriate bolometric correction we find that this AGN could easily dominate the FIR energetics. The nuclear reflection spectrum is seen through a relatively cold absorber with column density consistent with recent Spitzer observations. The soft X-ray emission, which may be thermal in nature and associated with star-forming activity, is seen unabsorbed. The soft X-rays and weak PAH features both give estimates of the star formation rate $\sim 300 M_{\odot}$ yr$^{-1}$, insufficient to power the FIR emission and supportive of the idea that this HLIRG is AGN-dominated.

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