The problem of radiation by the charged particles of the intergalactic medium (IGM) when a passing gravitational wave (GW) accelerates them is investigated. The largest acceleration (taking a charge from rest to a maximum speed which remains non-relativistic in the rest frame of the unperturbed spacetime) is found to be limited by the curvature of a propagating spherical gravitational wavefront. Interesting physics arises from the ensuing emission of radiation into the warm hot IGM, which to lowest order is a fully ionized hydrogen plasma with a frozen-in magnetic field B. It is found that for a vast majority of propagation directions, the radiation can penetrate the plasma at frequencies below the plasma frequency ω _p, provided ω < ω _b, where ω _b = eB/m _e satisfies ω _b < ω _p for typical IGM conditions. Moreover, the refractive index under such a scenario is n ≫ 1, resulting in an enhanced radiative dissipation of GW energy (relative to the vacuum scenario), which is more severe for electrons if both charge species are in thermal equilibrium and accelerated in the same way. The emission by the electrons then prevails, and is further amplified by coherent addition of amplitudes within the size one wavelength. The conversion of GWs of λ≳ 5 × 10¹³ cm to electromagnetic waves means such GWs can only propagate a distance ≲1 Gpc before being significantly damped by an IGM B field of ∼10⁻⁸ G. The low-frequency GWs targeted by pulsar-timing-arrays will not survive unless the IGM magnetic field is much lower than expected. The mHz frequency GW inspirals targeted by future space based detectors such as the Laser Interferometer Space Antenna remain intact and can be detected.

中文翻译：

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星际介质对长波引力波的阻尼

研究了当经过的引力波 (GW) 加速时星系际介质 (IGM) 的带电粒子的辐射问题。发现最大加速度（从静止带电到在未扰动时空的静止参考系中保持非相对论的最大速度）受到传播的球面引力波前曲率的限制。有趣的物理学源于随后辐射到温暖的 IGM 中的发射，它的最低阶是具有冻结磁场的完全电离的氢等离子体乙. 发现对于绝大多数传播方向，辐射可以以低于等离子体频率的频率穿透等离子体ω _p , 提供ω<ω _b , 其中ω _b =eB/米 _e满足ω _b <ω _p代表典型的 IGM 条件。此外，这种情况下的折射率为n≫ 1，导致 GW 能量的辐射耗散增强（相对于真空情况），如果两种电荷种类处于热平衡并以相同方式加速，这对电子来说更为严重。然后电子的发射占优势，并且通过在一个波长范围内的振幅的相干相加而进一步放大。GW的转换λ≳ 5 × 10 ¹³ cm 电磁波意味着此类 GW 在被 IGM 显着阻尼之前只能传播 ≲1 Gpc 的距离乙^{~10 -8} G的场。除非 IGM 磁场远低于预期，否则脉冲星定时阵列所瞄准的低频 GW 将无法生存。未来天基探测器（例如激光干涉仪空间天线）瞄准的 mHz 频率 GW 激励保持完好并且可以被探测到。