AKARI near-infrared spectroscopy of the aromatic and aliphatic hydrocarbon emission features in the galactic superwind of M 82
AKARI near-infrared spectroscopy of the aromatic and aliphatic hydrocarbon emission features in the galactic superwind of M 82
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DOI：
10.1051/0004-6361/201218904
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发表时间：
2012-03
影响因子：
6.5
通讯作者：
M. Yamagishi;H. Kaneda;D. Ishihara;T. Kondo;T. Onaka;Toyoaki Suzuki;Y. Minh
中科院分区：
文献类型：
--
作者：
M. Yamagishi;H. Kaneda;D. Ishihara;T. Kondo;T. Onaka;Toyoaki Suzuki;Y. Minh
目标。我们研究了M82星系超风中碳氢粒子的性质.方法.利用AKARI，我们对M 82的34个区域进行了近红外（2.5 - 4.5 μ m）光谱观测，包括它的北方和南方晕。结果许多光谱在3.3 μ m处显示出由于多环芳烃（PAH）的强发射，而在3.4 - 3.6 μ m处显示出由于脂肪族烃的相对弱的特征。特别是，我们清楚地检测到PAH 3.3 μ m的发射和晕区的3.4 - 3.6 μ m的功能，这是位于距离银河系中心2千秒差距。我们发现3.4 - 3.6 μ m特征与3.3 μ m特征强度的比值随离银心距离的增加而显著增加，而3.3 μ m特征与AKARI 7 μ m带强度的比值则不随离银心距离的增加而显著增加。结论.我们的研究结果清楚地证实了存在的小多环芳烃，即使在恶劣的环境中的晕的M 82。结果还表明，脂肪烃发射的3.4 - 3.6微米的功能是异常丰富的晕，这表明小的碳质颗粒是由较大的颗粒在银河系超级风粉碎。
Aims. We investigate the properties of hydrocarbon grains in the galactic superwind of M 82. Methods. With AKARI, we performed near-infrared (2.5 - 4.5 um) spectroscopic observations of 34 regions in M 82 including its northern and southern halos. Results. Many of the spectra show strong emission at 3.3 um due to polycyclic aromatic hydrocarbons (PAHs) and relatively weak features at 3.4 - 3.6 um due to aliphatic hydrocarbons. In particular, we clearly detect the PAH 3.3 um emission and the 3.4 - 3.6 um features in halo regions, which are located at a distance of 2 kpc away from the galactic center. We find that the ratios of the 3.4 - 3.6 um features to the 3.3 um feature intensity significantly increase with distance from the galactic center, while the ratios of the 3.3 um feature to the AKARI 7 um band intensity do not. Conclusions. Our results clearly confirm the presence of small PAHs even in a harsh environment of the halo of M 82. The results also reveal that the aliphatic hydrocarbons emitting the 3.4 - 3.6 um features are unusually abundant in the halo, suggesting that small carbonaceous grains are produced by shattering of larger grains in the galactic superwind.