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arXiv 1503.02538astro-ph.GA
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Messier 33:Halpha观测的动力学和质量模拟

Kinematics and Mass Modeling of Messier 33: Halpha observations

Zacharie Sie Kam, Claude Carignan, Laurent Chemin, Philippe Amram, Benoit Epinat

摘要:

作为一个长期项目的一部分,重新审视本星系群的大型盘星系的运动学和动力学,我们提出了第一个深,宽视场(42' x 56')的3D光谱调查的电离气体盘的梅西耶33。法布里-珀罗干涉测量法已被用于绘制其哈分布和运动学,其角分辨率(<3“)和分辨率(12600)是前所未有的,使用的是梅冈蒂克山天文台的1.6米望远镜。电离气体的分布遵循复杂的大尺度螺旋结构,这与已知的中性和分子气体盘的螺旋结构一致。对速度场的运动学分析表明,Ha盘的旋转中心与测光中心的距离为170 pc(天空投影距离),运动学长轴位置角和盘倾角与测光值非常吻合。在0 < R < 6.5 kpc时,Ha旋转曲线与HI旋转曲线非常吻合,但在R > 6.5 kpc时,Ha速度要高出10-20 km/s。造成这种差异的原因尚不清楚。速度色散曲线在16 km/s附近相对平坦,这是附近恒星形成星系盘速度色散的低端。一个很强的关系也被发现之间的哈速度色散和哈强度。质量模型是使用哈旋转曲线获得的,但是正如预期的那样,暗物质晕的参数并没有得到很好的约束,因为旋光曲线只延伸到8 kpc。

英文摘要:

As part of a long-term project to revisit the kinematics and dynamics of the large disc galaxies of the Local Group, we present the first deep, wide-field (42' x 56') 3D-spectroscopic survey of the ionized gas disc of Messier 33. Fabry-Perot interferometry has been used to map its Ha distribution and kinematics at unprecedented angular resolution (<3'') and resolving power (12600), with the 1.6m telescope at the Observatoire du Mont Megantic. The ionized gas distribution follows a complex, large-scale spiral structure, unsurprisingly coincident with the already-known spiral structures of the neutral and molecular gas discs. The kinematical analysis of the velocity field shows that the rotation center of the Ha disc is distant from the photometric center by 170 pc (sky projected distance) and that the kinematical major-axis position angle and disc inclination are in excellent agreement with photometric values. The Ha rotation curve agrees very well with the HI rotation curves for 0 < R < 6.5 kpc, but the Ha velocities are 10-20 km/s higher for R > 6.5 kpc. The reason for this discrepancy is not well understood. The velocity dispersion profile is relatively flat around 16 km/s, which is at the low end of velocity dispersions of nearby star-forming galactic discs. A strong relation is also found between the Ha velocity dispersion and the Ha intensity. Mass models were obtained using the Ha rotation curve but, as expected, the dark matter halo's parameters are not very well constrained since the optical rotation curve only extends out to 8 kpc.

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