论文标题
参数性重力波极化
Parametrizing gravitational-wave polarizations
论文作者
论文摘要
我们回顾了引力波（GW）极化的建模的形式主义，以及用于定义它们的坐标框架。在此过程中，我们阐明了“极化角度”的概念，并确定了三个概念上不同的定义。我们描述了它们如何相关以及它们在GW数据分析实践中如何出现，并详细解释了已成为Ligo-Virgo标准的相关惯例。此外，我们表明，任何GW信号都可以表示为椭圆形（即完全偏振）状态的叠加，并检查此类基本状态的特性和可能的参数化。我们讨论了完全偏振模式的各种常见参数化，并计算与它们相关的坐标转换的Jacobians。这使我们能够检查每个参数化对不同应用程序的适用性，包括未修饰或半模型的信号重建。我们指出，直接根据加号和跨模式幅度进行参数分析将倾向于隐式偏爱高信号功率，并且更喜欢沿预定义方向线性偏振的波。这使得它们是针对面对面或对抗来源的次优，这将是圆形极化的。我们讨论了替代参数化，应用扩展到连续波，响声研究和诸如贝叶斯波等未建模的分析。代码和其他材料可在https://github.com/maxisi/gwpols中提供。
We review the formalism underlying the modeling of gravitational wave (GW) polarizations, and the coordinate frames used to define them. In the process, we clarify the notion of "polarization angle" and identify three conceptually distinct definitions. We describe how those are related and how they arise in the practice of GW data analysis, explaining in detail the relevant conventions that have become the LIGO-Virgo standard. Furthermore, we show that any GW signal can be expressed as a superposition of elliptical (i.e., fully-polarized) states, and examine the properties and possible parametrizations of such elementary states. We discuss a variety of common parametrizations for fully-polarized modes, and compute Jacobians for the coordinate transformations relating them. This allows us to examine the suitability of each parametrization for different applications, including unmodeled or semimodeled signal reconstructions. We point out that analyses parametrized directly in terms of the plus and cross mode amplitudes will tend to implicitly favor high signal power, and to prefer linearly-polarized waves along a predefined direction; this makes them suboptimal for targeting face-on or face-off sources, which will tend to be circularly polarized. We discuss alternative parametrizations, with applications extending to continuous waves, ringdown studies, and unmodeled analyses like BayesWave. Code and additional material are made available in https://github.com/maxisi/gwpols.
