Gas and stellar spiral arms and their offsets in the grand-design spiral galaxy M51
Gas and stellar spiral arms and their offsets in the grand-design spiral galaxy M51
复制标题
宏伟设计螺旋星系 M51 中的气体和恒星旋臂及其偏移
DOI：
10.1093/mnras/stw2710
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发表时间：
2017
影响因子：
4.8
通讯作者：
Junichi
中科院分区：
文献类型：
--
作者：
Egusa;Fumi; Mentuch Cooper;Erin; Koda;Jin; Baba;Junichi
关于星际气体对具有准静止旋臂模式的引力势盘的响应的理论研究表明，由于旋臂上的驻波，气体经历了突然的压缩。这种机制被称为星系激波，它预测气体螺旋臂在旋转半径内随着半径的增加从恒星臂的下游向上游移动。为了研究这种机制是否在大设计螺旋星系M51中起作用，我们测量了其两个旋臂中恒星质量和气体质量分布峰值之间的方位角偏移。恒星质量分布由拟合光学和近红外图像的空间分辨光谱能量分布产生，而气体质量分布由高分辨CO和HI数据获得。对于内部区域（r≤150″），我们发现一条臂与星系激波一致，而另一条臂则不一致。对于外围区域，由于偏置值的范围较窄，星臂较弱，以及成功的偏置测量次数较少，结果不太确定。结果表明，两个内旋臂的性质是不同的，这可能是由于与伴星星系的相互作用。
Theoretical studies on the response of interstellar gas to a gravitational potential disc with a quasi-stationary spiral arm pattern suggest that the gas experiences a sudden compression due to standing shock waves at spiral arms. This mechanism, called a galactic shock wave, predicts that gas spiral arms move from downstream to upstream of stellar arms with increasing radius inside a corotation radius. In order to investigate if this mechanism is at work in the grand-design spiral galaxy M51, we have measured azimuthal offsets between the peaks of stellar mass and gas mass distributions in its two spiral arms. The stellar mass distribution is created by the spatially resolved spectral energy distribution fitting to optical and near infrared images, while the gas mass distribution is obtained by high-resolution CO and HI data. For the inner region (r≤ 150″), we find that one arm is consistent with the galactic shock while the other is not. For the outer region, results are less certain due to the narrower range of offset values, the weakness of stellar arms, and the smaller number of successful offset measurements. The results suggest that the nature of two inner spiral arms are different, which is likely due to an interaction with the companion galaxy.