论文标题
附近复合AGN-SB Galaxy NGC 4945中的多相ISM：大（PARSECS）尺度机械加热
The multi-phase ISM in the nearby composite AGN-SB galaxy NGC 4945: large (parsecs) scale mechanical heating
论文作者
论文摘要
我们旨在使用来自Herschel卫星的光谱和光度数据对附近复合AGN-SB Galaxy，NGC 4945进行全面研究。特别是，我们希望通过使用HIFI，PACS，SPIRE以及APEX数据对12^co发射在不同空间尺度下的空间分布进行多转化分析来表征该星系中的热结构。我们合并了12^CO/IR通量比和12 CO图像的LTE分析，以得出从<200 PC到2 kpc的空间尺度的星际介质（ISM）的热结构。从12^CO分析中，我们发现了派生温度分布和12^CO/IR比率的明显趋势。值得注意的是，在中间尺度（360 pc-1 kpc）下，我们在X射线流出方向上看到较大的温度，而在较小的尺度（<200 pc-360 pc）下，最高温度是从高J线中得出的最高温度，是朝向核的，而是朝向星系平面。从12CO多转变分析得出的热结构表明，诸如冲击或湍流之类的机械加热在NGC 4945的核中占主导地位的ISM加热，位于银河系中心100 pc以上。 Kazandjian等人进一步支持了这一结果。 2015年的模型，能够在包括机械加热机制时重现在High-J（PACS）12^CO转换下观察到的发射。冲击和/或湍流可能是由禁止的电势和流出产生的，在X射线中观察到。
We aim at carrying out a comprehensive study of the nearby composite AGN-SB galaxy, NGC 4945, using spectroscopic and photometric data from the Herschel satellite. In particular, we want to characterize the thermal structure in this galaxy by a multi-transitions analysis of the spatial distribution of the 12^CO emission at different spatial scales using HIFI, PACS, SPIRE as well as APEX data. We combined the 12^CO/IR flux ratios and the LTE analysis of the 12^CO images to derive the thermal structure of the Interstellar Medium (ISM) for spatial scales raging from <200 pc to 2 kpc. From the 12^CO analysis we found clear trend in the distribution of the derived temperatures and the 12^CO/IR ratios. It is remarkable that at intermediate scales (360 pc-1 kpc) we see large temperatures in the direction of the X-ray outflow while at smaller scales (<200 pc-360 pc), the highest temperature, derived from the high-J lines, is not found toward the nucleus, but toward the galaxy plane. The thermal structure derived from the 12CO multi-transition analysis suggests that mechanical heating, like shocks or turbulence, dominates the heating of the ISM in the nucleus of NGC 4945 located beyond 100 pc from the center of the galaxy. This result is further supported by the Kazandjian et al. 2015 models, which are able to reproduce the emission observed at high-J (PACS) 12^CO transitions when mechanical heating mechanisms are included. Shocks and/or turbulence are likely produced by the barred potential and the outflow, observed in X-rays.
