Framework for describing perturbations to the cosmic microwave background from a gravitational wave burst with memory
Framework for describing perturbations to the cosmic microwave background from a gravitational wave burst with memory
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DOI：
10.1103/physrevd.103.083515
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发表时间：
2020-09
影响因子：
5
通讯作者：
D. Madison
中科院分区：
文献类型：
--
作者：
D. Madison
有记忆的引力波爆发(BWM)可以在遥远的光源中产生可测量的、长时间的频移和永久性的角度偏转。这些扰动在天空中变化，具有特有的空间模式，并在很长一段时间内缓慢演变。在这项工作中，我们发展了可以用来描述BWM如何影响宇宙微波背景(CMB)中温度涨落的空间模式的形式。我们把注意力限制在平面引力波面上-这个假设极大地简化了必要的计算。使用CMB初级温度变化模式的玩具版本，我们证明了BWM可以将一定程度的球谐模式的能量混合到各种不同程度的模式中，而这些模式的$L$值非常不同。换言之，BWM对CMB在任何角度尺度上的扰动，具体取决于CMB在所有角度尺度上的不受扰动的特性。这里开发的工具将极大地促进未来对BWM引起的温度扰动的分析，这些分析结合了CMB背后的所有重要物理原理。
Gravitational wave bursts with memory (BWMs) can generate measurable, long-lived frequency shifts and permanent angular deflections in distant sources of light. These perturbations vary across the sky with a characteristic spatial pattern and evolve slowly over long periods of time. In this work, we develop formalism that can be used to describe how a BWM influences the spatial pattern of temperature fluctuations in the cosmic microwave background (CMB). We limit our attention to planar gravitational wave fronts---this assumption dramatically simplifies the necessary calculations. Using a toy version of the CMB's primary temperature variation pattern, we demonstrate that a BWM can mix power from a spherical harmonic mode of a certain degree into modes of various other degrees with vastly different $l$ values. In words, BWM-induced perturbations to the CMB at any angular scale depend in detail on the unperturbed character of the CMB on all angular scales. The tools developed herein will greatly facilitate future analyses of BWM-induced temperature perturbations that incorporate all of the important physics underlying the CMB.