论文标题
[C II]，[O I]和[O III]线的Herschel映射来自M31的周环区域
A Herschel mapping of [C ii], [O i] and [O iii] lines from the circumnuclear region of M31
论文作者
论文摘要
由多相星际培养基组成的M31的周环区域提供了中央超级黑洞及周围材料相互作用的特写视图。远红外（FIR）线结构线及其通量比可以用作该区域中性气体物理特性的诊断。在这里，我们介绍了[C II] 158 um，[O I] 63 UM和[O III] 88 UM线的第一个FIR光谱映射，该线路与Herschel空间天文台，覆盖约500 x 500 x 500 pc（2'x 2'）。沿着M31中央KPC沿所谓的核螺旋检测到所有这三个线的显着排放。三条线的空间分辨率下的速度场在〜50 pc的空间分辨率下具有广泛的一致性，并且与中央区域的先前CO（3-2）线观测值一致。结合了靶向磁盘上的其他五个磁场的现有[C II]和CO（3-2）观察结果，我们得出了[C II]/CO（3-2）通量比的径向分布，并发现该中心的比率高于磁盘，表明中央区域的气体密度和强辐射场。我们还发现，中央区域的[C II]/FIR比为5.4（+-0.8）x 10^-3，它在半半径中表现出越来越多的趋势，这表明从旧恒星种群对向中心的粉尘加热的贡献越来越大。
The circumnuclear region of M31, consisting of multiphase interstellar medium, provides a close-up view of the interaction of the central supermassive black hole and surrounding materials. Far-infrared (FIR) line structure lines and their flux ratios can be used as diagnostics of physical properties of the neutral gas in this region. Here we present the first FIR spectroscopic mapping of the circumnuclear region of M31 in [C ii] 158 um, [O i] 63 um and [O iii] 88 um lines with the Herschel Space Observatory, covering a ~500 x 500 pc (2' x 2') field. Significant emissions of all three lines are detected along the so-called nuclear spiral across the central kpc of M31. The velocity field under a spatial resolution of ~50 pc of the three lines are in broad consistency and also consistent with previous CO(3-2) line observations in the central region. Combined with existing [C ii] and CO(3-2) observations of five other fields targeting on the disk, we derived the radial distribution of [C ii]/CO(3-2) flux ratio, and found that this ratio is higher in the center than the disk, indicating a low gas density and strong radiation field in the central region. We also found that the [C ii]/FIR ratio in the central region is 5.4 (+-0.8) x 10^-3, which exhibits an increasing trend with the galactocentric radius, suggesting an increasing contribution from old stellar population to dust heating towards the center.
