ALMA observations of the dense and shocked gas in the nuclear region of NGC 4038 (Antennae galaxies)
ALMA observations of the dense and shocked gas in the nuclear region of NGC 4038 (Antennae galaxies)
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ALMA 对 NGC 4038（触角星系）核区致密冲击气体的观测
DOI：
10.1093/pasj/psw110
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发表时间：
2017
影响因子：
2.3
通讯作者：
Shinya
中科院分区：
文献类型：
--
作者：
Ueda;Junko; Watanabe;Yoshimasa; Iono;Daisuke; Wilner;David J.; Fazio;Giovanni G.; Ohashi;Satoshi; Kawabe;Ryohei; Saito;Toshiki; Komugi;Shinya
我们提供了从CN，HCN，HCO+，CH 3OH和HNCO五个分子获得的毫米辐射的1“（<100 pc）分辨率图，这些分子朝向NGC 4038，这是中期合并的北方星系，Atacama大型毫米/亚毫米阵列。在NGC 4038的核区域首次检测到三个分子（CN，CH 3OH和HNCO）。高分辨率映射揭示了不同分子种类和连续发射分布的系统差异。由3 mm和850 μm连续辐射确定的活跃恒星形成区与HCN（1-0）和CO（3-2）峰相关的富气体区相偏移。CN（1-0）/HCN（1-0）谱线比在恒星形成区增强（CN/HCN = 0.8-1.2），表明该区域是光子主导的。在CO（3-2）峰的06（1060 pc）半径范围内的大分子气体质量（108 M H2O）和由HCN（1-0）/CO（3-2）线比率所建议的高密度气体分数（>20%）可能预示着那里未来强烈的星星形成的爆发。在CH 3OH和HNCO发射中追踪到的冲击气体表明亚千秒差距尺度的分子冲击。我们认为，分子冲击可能是由流入的气体和中心的大质量分子复合物之间的碰撞驱动的。
We present 1″(<100 pc) resolution maps of millimeter emission from five molecules—CN, HCN, HCO+, CH3OH, and HNCO—obtained towards NGC 4038, which is the northern galaxy of the mid-stage merger, Antennae galaxies, with the Atacama Large Millimeter/submillimeter Array. Three molecules (CN, CH3OH, and HNCO) were detected for the first time in the nuclear region of NGC 4038. High-resolution mapping reveals a systematic difference in distributions of different molecular species and continuum emission. Active star-forming regions identified by the 3 mm and 850 μm continuum emission are offset from the gas-rich region associated with the HCN (1–0) and CO (3–2) peaks. The CN (1–0)/HCN (1–0) line ratios are enhanced (CN/HCN ≃ 0.8–1.2) in the star-forming regions, suggesting that the regions are photon dominated. The large molecular gas mass (108M⊙) within a 06 (∼60 pc) radius of the CO (3–2) peak and a high dense gas fraction (>20%) suggested by the HCN (1–0)/CO (3–2) line ratio may signify a future burst of intense star formation there. The shocked gas traced in the CH3OH and HNCO emission indicates sub-kpc-scale molecular shocks. We suggest that the molecular shocks may be driven by collisions between inflowing gas and the central massive molecular complex.