In the Chandra Deep Field-South 1 Ms exposure, we have found, at redshift 3.700 +- 0.005, the most distant type 2 active galactic nucleus ever detected. It is the source with the hardest X-ray spectrum with redshift z > 3. Theo optical spectrum has no detected continuum emission to a 3σ detection limit of ～3 x 10~(-19) ergs s~(-1) cm~(-2) A~(-1) and shows narrow lines of Lyα, C Ⅳ, N Ⅴ, He Ⅱ, O Ⅵ, [O Ⅲ], and C Ⅲ]. Their FWHM line widths have a range of ～700~2300 km s~(-1) with an average of approximately ～1500 km s~(-1). The emitting gas is metal-rich (Z approx= 2.5-3 Z_☉). In the X-ray spectrum of 130 counts in the 0.5-7 keV band, there is evidence for intrinsic absorption with N_H approx> 10~(24) cm~(-2). An iron Kα line with rest-frame energy and equivalent width of ～6.4 keV and ～1 keV, respectively, in agreement with the obscuration scenario, is detected a a 2σ level. If confirmed by our forthcoming XMM-Newton observations, this would be the highest redshift detection of Fe Kα. Depending on the assumed cosmology and the X-ray transfer model, the 2-10 keV rest frame luminosity corrected for absorption is ～10~(45+-0.5) ergs cm~(-2) s~(-1), which makes our source a classic example of the long-sought type 2 QSO. From standard population synthesis models, these sources are expected to account for a relevant fraction of the black hole-powered QSO distribution at high redshift.
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机译：在钱德拉深场-南1 Ms曝光中，我们发现在红移3.700±0.005处，有史以来检测到的最遥远的2型活跃银河核。它是X射线光谱最硬的源，其红移z>3。该光谱没有检测到连续发光，检测到的3σ检测极限为〜3 x 10〜（-19）ers s〜（-1）cm〜（ -2）A〜（-1）并显示Lyα，CⅣ，NⅤ，HeⅡ，OⅥ，[OⅢ]和CⅢ]的窄线。它们的FWHM线宽范围为〜700〜2300 km s〜（-1），平均约为〜1500 km s〜（-1）。发射气体富含金属（Z大约= 2.5-3Z_☉）。在0.5-7 keV波段的130个计数的X射线光谱中，有证据表明N_H的固有吸收约为10〜（24）cm〜（-2）。一条铁架Kα线具有静止框架能量，等效宽度分别为〜6.4 keV和〜1 keV，与遮蔽方案一致，被检测为2σ水平。如果得到我们即将进行的XMM-Newton观测的证实，这将是FeKα的最高红移检测。根据假设的宇宙学和X射线传输模型，经校正吸收后的2-10 keV静止帧发光度约为〜10〜（45 + -0.5）ergs cm〜（-2）s〜（-1），这使得我们的资料来源是长期寻求的2型QSO的经典示例。根据标准的人口综合模型，这些来源预计将占高红移下黑洞供电的QSO分布的相关部分。
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