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arXiv 1010.3530astro-ph.CO
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eCDFS中亚毫米LABOCA星系的X射线观测

X-ray observations of sub-mm LABOCA galaxies in the eCDFS

I. Georgantopoulos, E. Rovilos, A. Comastri

摘要:

本文研究了LABOCA巡天的126个亚毫米星系在CDFS和eCDFS区的X射线性质。SMG被认为经历了大规模的恒星形成。我们的目标是研究恒星形成是否与活动星系核活动共存,确定高度模糊的活动星系核的比例,并最终获得这些来源的主导动力机制的想法。使用斯皮策和SMG的射电弧秒位置,我们发现了14个具有显着X射线探测的源。对于大多数这些只有光度红移可用,其中值红移约为2.3。考虑到CDFS区域的X射线观测最深,我们估计活动星系核中的X射线比例<26+/-9%。大多数与SMG有关的活动星系核X射线的X射线光谱特性与高遮蔽度(10^23 cm-2)相一致,但没有明确的证据表明存在康普顿厚度的源。详细的光谱能量分布拟合表明,大部分的总红外光度起源于恒星形成的过程中,虽然通常是一个环面组件。最后,对未检测到的X射线SMG的叠加分析揭示了软(0.5-2 keV)和硬(2-5 keV)X射线带中的边缘信号。堆叠信号的硬度比相对较软(-0.40+/-0.10),对应于约1.6的光子指数。这与未探测到的X射线SMG中康普顿厚度源的高比例相矛盾。

英文摘要:

We explore the X-ray properties of the 126 sub-mm galaxies (SMGs) of the LABOCA survey in the CDFS and the eCDFS regions. SMGs are believed to experience massive episodes of star-formation. Our goal is to examine whether star-formation coexists with AGN activity, determine the fraction of highly obscured AGN and finally to obtain an idea of the dominant power-mechanism in these sources. Using Spitzer and radio arc-second positions for the SMGs, we find 14 sources with significant X-ray detections. For most of these there are only photometric redshifts available, with their median redshift being ~2.3. Taking into account only the CDFS area which has the deepest X-ray observations, we estimate an X-ray AGN fraction of <26+/-9 % among SMGs. The X-ray spectral properties of the majority of the X-ray AGN which are associated with SMGs are consistent with high obscuration, 10^23 cm-2, but there is no unambiguous evidence for the presence of Compton-thick sources. Detailed Spectral Energy Distribution fittings show that the bulk of total IR luminosity originates in star-forming processes, although a torus component is usually present. Finally, stacking analysis of the X-ray undetected SMGs reveals a signal in the soft (0.5-2 keV) and marginally in the hard (2-5 keV) X-ray band. The hardness ratio of the stacked signal is relatively soft (-0.40+/-0.10) corresponding to a photon index of ~1.6. This argues against a high fraction of Compton-thick sources among the X-ray undetected SMGs.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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