论文标题
标量引起的重力波$λ$ CDM宇宙学
Scalar-Induced Gravitational Waves in a $Λ$CDM Cosmology
论文作者
论文摘要
我们重新考虑了在空间平坦的Friedmann-Lema-Robertson-Walker-walker spacetimes中，由标量扰动引起的引力波谱，重点介绍了物质和$λ$二世时代的时期。在物质统治期间，亚匹配模式不是免费的，并且通常将张量扰动的衍生物应用近似值是有缺陷的。我们分析表明，这导致能量密度光谱的显着高估。此外，我们证明了依赖量规的非振动张量扰动出现在宇宙常数的存在下。在补充分析计算的情况下，我们根据当前的频谱计算了类似普兰克的$λ$ CDM宇宙学，发现在物质和$λ$统治中，在保形牛顿牛场的过渡期间出现了非振荡的增长模式。
We reconsider the gravitational wave spectrum induced by scalar perturbations in spatially flat Friedmann-Lemaître-Robertson-Walker spacetimes, focusing on the matter- and $Λ$-dominated epochs. During matter domination, sub-horizon modes are not free and a commonly applied approximation for the derivative of the tensor perturbation is flawed. We show analytically that this leads to a significant overestimation of the energy density spectrum. In addition, we demonstrate that gauge-dependent non-oscillating tensor perturbations appear in the presence of a cosmological constant. Complementing the analytical calculations, we compute the according present-day spectrum numerically for a Planck-like $Λ$CDM cosmology, finding that non-oscillating growing modes appear during the transition between matter and $Λ$ domination in conformal Newtonian gauge.
