标题： 弯曲时空中的引力波与磁流体动力学波在大尺度磁场存在下的情况 显示英文标题

标题： Gravitational versus magnetohydrodynamic waves in curved spacetime in the presence of large-scale magnetic fields

摘要： 广义相对论（GR）磁流体动力学（MHD）方程对于导电等离子体流体是在由Thorne度规张量描述的弯曲时空中推导和讨论的，即一类由于存在环境的大尺度磁场而具有固有各向异性的宇宙学模型。 在此框架中，检查驱动此类模型演化的磁化等离子体流体是否可以被瞬态、平面极化的引力波（GW）激发。 为此，我们考虑运动的扰动方程组，并对其进行数值积分，以研究由GW传播引发的不稳定性的发展。 特别是，我们检查电场和/或磁场的扰动在多大程度上可以由于从GW到电磁（EM）自由度的潜在能量转移而被放大。 扰动量的发展取决于四个自由参数，即流体的电导率，$\sg$，声速平方，$\frac{1}{3}< \left ( \frac{C_s}{c} \right )^2 \equiv \gm < 1$，在此模型中也可作为固有各向异性的度量，GW频率，$\om_{g}$，以及与磁场方向相关的传播角度，$\theta$。 我们发现，在考虑的各向异性磁化介质中，GW传播确实会激发多种MHD模式，换句话说，存在从引力到电磁自由度的能量转移，这可能导致该位置带电粒子的加速以及随后的GW衰减。 显示英文摘要

摘要： The general-relativistic (GR) magnetohydrodynamic (MHD) equations for a conductive plasma fluid are derived and discussed in the curved spacetime described by Thorne's metric tensor, i.e., a family of cosmological models with inherent anisotropy due to the existence of an ambient, large-scale magnetic field. In this framework, it is examined whether the magnetized plasma fluid that drives the evolution of such a model can be subsequently excited by a transient, plane-polarized gravitational wave (GW) or not. To do so, we consider the associated set of the perturbed equations of motion and integrate it numerically, to study the evolution of instabilities triggered by the GW propagation. In particular, we examine to what extend perturbations of the electric- and/or the magnetic field can be amplified due to a potential energy transfer from the GW to the electromagnetic (EM) degrees of freedom. The evolution of the perturbed quantities depends on four free parameters, namely, the conductivity of the fluid, $\sg$, the speed-of-sound-square, $\frac{1}{3}< \left ( \frac{C_s}{c} \right )^2 \equiv \gm < 1$, which in this model may serve also as a measure of the inherent anisotropy, the GW frequency, $\om_{g}$, and the associated angle of propagation with respect to the direction of the magnetic field, $\theta$. We find that, the GW propagation in the anisotropic magnetized medium under consideration does excite several MHD modes, in other words, there is energy transfer from the gravitational to the EM degrees of freedom that could result in the acceleration of charged particles at the spot and in the subsequent damping of the GW.