M51图形速度的径向相关性
Radial Dependence of the Pattern Speed of M51
摘要：
宏伟的螺旋星系M51长期以来一直是螺旋结构理论的重要目标。对这一标志性螺旋的研究可以解决强螺旋结构是短暂的（例如相互作用驱动的）还是持久的问题。作为M51结构起源的线索，我们使用径向TWR方法研究了螺旋图案速度径向变化的证据。我们实现了CO观测跟踪ISM占主导地位的分子成分的方法。来自该方法的数值实现的结果-与平滑固有噪声解的正则化相结合-表明在我们导出的主轴PA=170 °处4kpc内的两个不同的模式速度，两者都以共转结束，并且都显著高于常规采用的全局值。旋转曲线的检查表明，2 kpc内部的模式速度缺乏ILR，与HST近红外观测中看到的领先结构一致。我们还发现了一个较低的模式之间的速度为4和5.3千秒差距通过延长正规化区测量的初步证据。与原始TW方法一样，主轴位置角（PA）的不确定性是计算中最大的误差来源;在本研究中，其中δPA=+/-5 deg.在PA=170 °时，对速度参数引入~20%的误差。该标准不确定度的附件，PA=175度的溶液。(also数据所承认的）在4kpc内仅表现出一种模式速度，并且我们在径向变化PA的语义下考虑这种情况。
英文摘要：
The grand-design spiral galaxy M51 has long been a crucial target for theories of spiral structure. Studies of this iconic spiral can address the question of whether strong spiral structure is transient (e.g. interaction-driven) or long-lasting. As a clue to the origin of the structure in M51, we investigate evidence for radial variation in the spiral pattern speed using the radial Tremaine-Weinberg (TWR) method. We implement the method on CO observations tracing the ISM-dominant molecular component. Results from the method's numerical implementation--combined with regularization, which smooths intrinsically noisy solutions--indicate two distinct patterns speeds inside 4 kpc at our derived major axis PA=170 deg., both ending at corotation and both significantly higher than the conventionally adopted global value. Inspection of the rotation curve suggests that the pattern speed interior to 2 kpc lacks an ILR, consistent with the leading structure seen in HST near-IR observations. We also find tentative evidence for a lower pattern speed between 4 and 5.3 kpc measured by extending the regularized zone. As with the original TW method, uncertainty in major axis position angle (PA) is the largest source of error in the calculation; in this study, where δPA=+/-5 deg. a ~20% error is introduced to the parameters of the speeds at PA=170 deg. Accessory to this standard uncertainty, solutions with PA=175 deg. (also admitted by the data) exhibit only one pattern speed inside 4 kpc, and we consider this circumstance under the semblance of a radially varying PA.
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