Primordial power spectrum from a matter-ekpyrotic scenario in loop quantum cosmology
Primordial power spectrum from a matter-ekpyrotic scenario in loop quantum cosmology
复制标题
环量子宇宙学中物质火场景的原始功率谱
DOI：
10.1142/9789811269776_0348
复制
发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Singh, Parampreet
中科院分区：
文献类型：
--
作者：
Li, Bao-Fei;Saini, Sahil;Singh, Parampreet
一般的物质反弹的情况下，包括Ekpyrotic场，以避免各向异性的不稳定性，研究了在一个循环量化的各向同性和均匀FLRW设置。物质反弹的情况下提供了一个方便的方法，包括量子校正反弹的扰动起源于遥远的过去，这也产生了一个标度不变的功率谱。LQC为研究物质反弹场景中的量子校正提供了正确的设置，因为LQC中的反弹完全是由于量子几何效应而发生的，而不需要任何奇异的物质场来避免奇异性。详细探讨了这种一般的物质Ekpyrotic方案在空间平坦FLRW时空中的LQC充满最小耦合尘埃和Ekpyrotic标量场的帮助下，研究了数值模拟。背景动态的各种功能被证明是强大的初始条件和参数选择的变化下。我们使用修饰度规的方法的扰动，并获得一个标度不变的功率谱模式退出视界的尘埃为主的收缩阶段。在以往的研究中，考虑一个恒定的状态方程的Ekpyrotic字段，我们发现，功率谱的大小变化的演变过程中。功率谱的标度不变部分在反弹状态下也经历了其幅度的快速增加，而其标度不变性不受影响。我们认为，除了增加的幅度，反弹制度可能只会大大影响规模不变制度以外的模式。然而，发现光谱指数太接近于1，因此与观测约束不一致，需要进一步修改模式。
The general matter bounce scenario, including an Ekpyrotic field to avoid anisotropic instabilities, is studied in a loop quantized isotropic and homogeneous FLRW setting. The matter bounce scenario provides a convenient way to include quantum corrections from the bounce in the perturbations originating in the far past, which also produce a scale invariant power spectrum. LQC provides the right setting for studying quantum corrections in a matter bounce scenario as the bounce in LQC occurs entirely due to quantum geometrical effects without needing any exotic matter fields to avoid the singularity. A detailed exploration of this general matter-Ekpyrotic scenario in spatially flat FLRW spacetime in LQC filled with minimally coupled dust and Ekpyrotic scalar field is studied with the help of numerical simulations. Various features of the background dynamics are shown to be robust under variations in initial conditions and choice of parameters. We use the dressed metric approach for the perturbations and obtain a scale invariant power spectrum for modes exiting the horizon in the dust dominated contracting phase. In contrast to previous studies considering a constant equation of state for the Ekpyrotic field, we found that the magnitude of the power spectrum changes during the evolution. The scale invariant section of the power spectrum also undergoes a rapid increase in its magnitude in the bounce regime, while its scale invariance is unaffected. We argue that apart from increasing the magnitude, the bounce regime may only substantially affect the modes outside the scale invariant regime. However, the spectral index is found to be too close to unity, thus inconsistent with the observational constraints, necessitating further modifications of the model.