WATER VAPOR EMISSION REVEALS A HIGHLY OBSCURED, STAR-FORMING NUCLEAR REGION IN THE QSO HOST GALAXY APM 08279+5255 AT z = 3.9
WATER VAPOR EMISSION REVEALS A HIGHLY OBSCURED, STAR-FORMING NUCLEAR REGION IN THE QSO HOST GALAXY APM 08279+5255 AT z = 3.9
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DOI：
10.1088/2041-8205/741/2/l38
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发表时间：
2011-06
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影响因子：
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通讯作者：
P. P. van der Werf-P.;A. Berciano Alba;M. Spaans;A. F. Loenen;R. Meijerink;D. Riechers;P. Cox;A. Weiss;F. Walter
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作者：
P. P. van der Werf-P.;A. Berciano Alba;M. Spaans;A. F. Loenen;R. Meijerink;D. Riechers;P. Cox;A. Weiss;F. Walter
我们在引力透镜Z=3.9QSO宿主星系APM 08279+5255中，从能级Eu/k=101-454K探测到水蒸气的四条旋转发射线。当最低的H2 O谱线在温暖、致密的气体(氢核密度，气体温度Tg∼10 5±2 1K)中被碰撞激发时，我们发现较高的谱线的激发是由强烈的局域红外辐射场主导的。由于只有碰撞激发的发射有助于气体冷却，我们得出结论，H2 O不是热分子气体的重要冷却剂。我们的激发模型要求辐射激发气体位于高100μm不透明度的扩展区域(τ100=0.9±0.2)。在局部，这种扩展的红外不透明区域只在超发光红外星系的核中发现。我们提出了一个模型，在这个模型中，被类星体核的X射线辐射场穿透的红外不透明的环核云团，包含了起源于H2 O发射的大质量恒星形成的团块。来自强烈的局部红外辐射场的辐射压力比热气体压力高出大约一个数量级，这表明在这些星团中形成的恒星接近爱丁顿极限。
We present the detection of four rotational emission lines of water vapor, from energy levels Eu/k = 101–454 K, in the gravitationally lensed z = 3.9 QSO host galaxy APM 08279+5255. While the lowest H2 O lines are collisionally excited in clumps of warm, dense gas (density of hydrogen nuclei , gas temperature Tg ∼ 105 ± 21 K), we find that the excitation of the higher lines is dominated by the intense local infrared radiation field. Since only collisionally excited emission contributes to gas cooling, we conclude that H2 O is not a significant coolant of the warm molecular gas. Our excitation model requires the radiatively excited gas to be located in an extended region of high 100 μ m opacity (τ100 = 0.9 ± 0.2). Locally, such extended infrared-opaque regions are found only in the nuclei of ultraluminous infrared galaxies. We propose a model where the infrared-opaque circumnuclear cloud, which is penetrated by the X-ray radiation field of the QSO nucleus, contains clumps of massive star formation where the H2 O emission originates. The radiation pressure from the intense local infrared radiation field exceeds the thermal gas pressure by about an order of magnitude, suggesting close to Eddington-limited star formation in these clumps.