论文标题
来自水磁湍流的重力波光谱的低频尾
Low frequency tail of gravitational wave spectra from hydromagnetic turbulence
论文作者
论文摘要
早期宇宙中的流体动力学和磁流失动力动力湍流可以驱动重力波（GWS），并将其谱图烙印到GWS的频谱上，今天仍然可以观察到。我们研究了从螺旋和非螺旋初始磁场从自由衰减的磁性水力动力湍流中生产的GW背景。为了了解产生的GW光谱，我们基于磁应力张量的演变而开发了一个简单的模型。我们发现，如果我们考虑了数值模拟中应力谱的低频尾巴的详细时间演化，则在该模型中获得的GW光谱再现了在数值模拟中获得的GW光谱。我们还表明，对于相同的初始磁能光谱，对于螺旋和非螺旋病例而产生的GW频谱的形状不同。这种差异可以帮助将螺旋和非螺旋初始磁场与GWS的极化背景区分开 - 尤其是当无法直接检测到预期的圆极化时。
Hydrodynamic and magnetohydrodynamic turbulence in the early Universe can drive gravitational waves (GWs) and imprint their spectrum onto that of GWs, which might still be observable today. We study the production of the GW background from freely decaying magnetohydrodynamic turbulence from helical and nonhelical initial magnetic fields. To understand the produced GW spectra, we develop a simple model on the basis of the evolution of the magnetic stress tensor. We find that the GW spectra obtained in this model reproduce those obtained in numerical simulations if we consider the detailed time evolution of the low-frequency tail of the stress spectrum from numerical simulations. We also show that the shapes of the produced GW frequency spectra are different for helical and nonhelical cases for the same initial magnetic energy spectra. Such differences can help distinguish helical and nonhelical initial magnetic fields from a polarized background of GWs -- especially when the expected circular polarization cannot be detected directly.
