Messier 31的HI运动学和动力学
HI kinematics and dynamics of Messier 31
摘要：
[摘要]我们提出了一个新的深度21厘米的仙女座星系的调查，基于高分辨率的观测与综合望远镜和26米天线在DRAO。分析了圆盘的HI分布和运动学，给出了圆盘的基本动力学性质。旋转曲线测量到38千秒差距，显示出核峰值，约4千秒差距的下降，两个不同的平坦部分和最外层区域的增加。除了最里面的区域外，气体旋转的轴对称性很好。HI盘的非常强的翘曲被证明。中心区域的倾斜度小于平均椎间盘倾斜度，而外部区域的倾斜度更大。本文介绍了LCDM NFW、Einasto和含重子分量的伪等温暗物质晕的质量分布模型。它们不能精确地再现旋转曲线的形状。在各种形状的晕之间没有测量到显著差异。半径为38 kpc的M31的动力学质量为（4.7 +/- 0.5）x 10^11 Msol。暗物质成分的质量几乎是这个半径内重子质量的4倍。在维里半径内，总质量为1.0 x 10^12 Msol。在数据立方体中发现了新的HI结构，例如每个光谱检测到多达5个HI成分，这在其他星系中非常罕见。最引人注目的新HI结构是薄HI马刺和在磁盘外围的外部臂。这些马刺和外部恒星团之间的关系是有证据的。外臂长32千秒差距，位于星系的远端，在星系的另一端没有明显的对应物。其运动学明显不同于外侧相邻椎间盘。这两种HI扰动都可能是由于与星系同伴的潮汐相互作用造成的。
英文摘要：
[Abridged] We present a new deep 21-cm survey of the Andromeda galaxy, based on high resolution observations performed with the Synthesis Telescope and the 26-m antenna at DRAO. The HI distribution and kinematics of the disc are analyzed and basic dynamical properties are given. The rotation curve is measured out to 38 kpc, showing a nuclear peak, a dip around 4 kpc, two distinct flat parts and an increase in the outermost regions. Except for the innermost regions, the axisymmetry of the gas rotation is very good. A very strong warp of the HI disc is evidenced. The central regions appear less inclined than the average disc inclination, while the outer regions appear more inclined. Mass distribution models by LCDM NFW, Einasto or pseudo-isothermal dark matter halos with baryonic components are presented. They fail to reproduce the exact shape of the rotation curve. No significant differences are measured between the various shapes of halo. The dynamical mass of M31 enclosed within a radius of 38 kpc is (4.7 +/- 0.5) x 10^11 Msol. The dark matter component is almost 4 times more massive than the baryonic mass inside this radius. A total mass of 1.0 x 10^12 Msol is derived inside the virial radius. New HI structures are discovered in the datacube, like the detection of up to five HI components per spectrum, which is very rarely seen in other galaxies. The most remarkable new HI structures are thin HI spurs and an external arm in the disc outskirts. A relationship between these spurs and outer stellar clumps is evidenced. The external arm is 32 kpc long, lies on the far side of the galaxy and has no obvious counterpart on the other side of the galaxy. Its kinematics clearly differs from the outer adjacent disc. Both these HI perturbations could result from tidal interactions with galaxy companions.
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