论文标题
早期辐射时代的重力波的改良传播
Modified propagation of gravitational waves from the early radiation era
论文作者
论文摘要
我们研究了从辐射时代早期到今天的重力理论，从辐射时代到今天的宇宙学重力波（GW）背景的传播。与一般相对论（GR）相比，我们研究了修改重力参数的效果，例如GW摩擦$α_ {\ rm m} $和张量速度过剩$α_ {\ rm t} $，对当今的GW频谱具有。我们使用WKB估计值，该估计值提供了一个分析描述，但在超级方尺度上失败，也可以在数值模拟中失败，使我们能够超越WKB近似值。 We show that a constant $α_{\rm T}$ makes relatively insignificant changes to the GR solution, especially taking into account the constraints on its value from GW observations by the LIGO--Virgo collaboration, while $α_{\rm M}$ can introduce modifications to the spectral slopes of the GW energy spectrum in the low-frequency regime depending on the considered time evolution of $α_ {\ rm m} $。后一种效果是在所有尺度上都可以通过WKB近似预测的阻尼或生长的其他效果。鉴于Pulsar定时阵列（PTA）的最新观察以及未来检测器（例如SKA，Lisa，decigo，bbo或et）的潜在观察结果，我们表明，在大多数情况下，在大多数情况下，限制无法对$α_{\ rm m} $ and gw gw Entirm $ $ $ $ { GW}^*$分别，但仅在两者的组合效果上，除非在不同的频率范围内观察到信号。特别是，我们对报告的PTA观察结果的综合效应提供了一些限制。
We study the propagation of cosmological gravitational wave (GW) backgrounds from the early radiation era until the present day in modified theories of gravity. Comparing to general relativity (GR), we study the effects that modified gravity parameters, such as the GW friction $α_{\rm M}$ and the tensor speed excess $α_{\rm T}$, have on the present-day GW spectrum. We use both the WKB estimate, which provides an analytical description but fails at superhorizon scales, and numerical simulations that allow us to go beyond the WKB approximation. We show that a constant $α_{\rm T}$ makes relatively insignificant changes to the GR solution, especially taking into account the constraints on its value from GW observations by the LIGO--Virgo collaboration, while $α_{\rm M}$ can introduce modifications to the spectral slopes of the GW energy spectrum in the low-frequency regime depending on the considered time evolution of $α_{\rm M}$. The latter effect is additional to the damping or growth occurring equally at all scales that can be predicted by the WKB approximation. In light of the recent observations by pulsar timing array (PTA) collaborations, and the potential observations by future detectors such as SKA, LISA, DECIGO, BBO, or ET, we show that, in most of the cases, constraints cannot be placed on the effects of $α_{\rm M}$ and the initial GW energy density $\mathcal{E}_{\rm GW}^*$ separately, but only on the combined effects of the two, unless the signal is observed at different frequency ranges. In particular, we provide some constraints on the combined effects from the reported PTA observations.
