Infrared Molecular Starburst Fingerprints in Deeply Obscured (Ultra)Luminous Infrared Galaxy Nuclei
Infrared Molecular Starburst Fingerprints in Deeply Obscured (Ultra)Luminous Infrared Galaxy Nuclei
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深暗（超）发光红外星系核中的红外分子星爆指纹
DOI：
10.1086/512050
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发表时间：
2006
期刊：
影响因子：
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通讯作者：
E. F. Dishoeck
中科院分区：
文献类型：
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作者：
F. Lahuis;H. Spoon;A. Tielens;S. Doty;L. Armus;V. Charmandaris;V. Charmandaris;J. Houck;P. Stäuber;E. F. Dishoeck
斯皮策太空望远镜的高分辨率光谱显示了气体C2 H2，HCN和CO2分子朝向深度模糊（U）LIRG核样本的振动-旋转吸收带。观察到的带揭示了存在的致密（n = 107 cm-3），温暖（特克斯= 200-700 K）的分子气体，这些分子的高柱密度范围从几个1015至1017 cm-2。相对于H2的丰度，从硅酸盐光学深度推断，范围从~10-7到10-6，与温度无关。理论研究表明，C2 H2和HCN的高丰度排除了与活动星系核周围的环相关联的X射线主导区（XDR）作为这种致密的温暖分子气体的起源。在所谓的热核阶段，银河系的大质量原恒星具有类似的物理特征，在热阶段具有相当高的C2 H2，HCN和CO2丰度。在低温（Tex = 400 K）下，（U）LIRG的C2 H2和HCN丰度以及C2 H2/CO2和HCN/CO2比值都比（U）LIRG高得多.我们认为，温暖致密的分子气体揭示了中红外吸收线是与一个阶段的深埋星星形成，在极端的压力和密度的核星爆环境抑制了H II地区的扩张和全球性的破坏恒星形成的分子云核心，并“困”的星星形成过程中的“扩展”热核心阶段。
High-resolution spectra of the Spitzer Space Telescope show vibration-rotation absorption bands of gaseous C2H2, HCN, and CO2 molecules toward a sample of deeply obscured (U)LIRG nuclei. The observed bands reveal the presence of dense (n ≳ 107 cm-3), warm (Tex = 200-700 K) molecular gas with high column densities of these molecules ranging from a few 1015 to 1017 cm-2. Abundances relative to H2, inferred from the silicate optical depth, range from ~10-7 to 10-6 and show no correlation with temperature. Theoretical studies show that the high abundances of both C2H2 and HCN exclude an X-ray dominated region (XDR) associated with the toroid surrounding an AGN as the origin of this dense warm molecular gas. Galactic massive protostars in the so-called hot-core phase have similar physical characteristics with comparable high abundances of C2H2, HCN, and CO2 in the hot phase. However, the abundances of C2H 2 and HCN and the C2H2/CO2 and HCN/CO2 ratios are much higher toward the (U)LIRGs in the cooler (Tex ≲ 400 K) phase. We suggest that the warm dense molecular gas revealed by the mid-IR absorption lines is associated with a phase of deeply embedded star formation, where the extreme pressures and densities of the nuclear starburst environment have inhibited the expansion of H II regions and the global disruption of the star-forming molecular cloud cores and have "trapped" the star formation process in an "extended" hot-core phase.