从射电干涉仪精确恢复HI速度色散
Accurate recovery of HI velocity dispersion from radio interferometers
摘要：
气体速度色散测量旋转盘的无序运动的量。这个参数的准确估计是至关重要的，因为它直接关系到磁盘的稳定性和恒星的形成。从氢原子HI 21 cm线的宽度可以推断出气体速度分散的全局测量。我们探讨了如何在HI立方体的生产中涉及的几个系统的影响影响HI速度色散的估计。我们这样做是通过比较HI速度分散来自不同类型的数据立方体提供的HI附近星系调查（东西）。我们发现，残余缩放立方体最好恢复HI速度色散，独立的加权方案使用和大范围的信噪比。对于其中脏光束与高斯光束基本上不同的HI观测，速度色散值被高估，除非立方体被清洁接近（例如，~1.5倍）的噪音水平。
英文摘要：
Gas velocity dispersion measures the amount of disordered motions of a rotating disk. Accurate estimates of this parameter are of the utmost importance because it is directly linked to disk stability and star formation. A global measure of the gas velocity dispersion can be inferred from the width of the atomic hydrogen HI 21 cm line. We explore how several systematic effects involved in the production of HI cubes affect the estimate of HI velocity dispersion. We do so by comparing the HI velocity dispersion derived from different types of data cubes provided by The HI Nearby Galaxy Survey (THINGS). We find that residual-scaled cubes best recover the HI velocity dispersion, independent of the weighting scheme used and for a large range of signal-to-noise ratio. For HI observations where the dirty beam is substantially different from a Gaussian, the velocity dispersion values are overestimated unless the cubes are cleaned close to (e.g., ~1.5 times) the noise level.
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