Detectability of inflation-produced gravitational waves
Detectability of inflation-produced gravitational waves
复制标题
暴胀产生的引力波的可探测性
DOI：
--
复制
发表时间：
1996
期刊：
影响因子：
--
通讯作者：
M. Turner
中科院分区：
文献类型：
--
作者：
M. Turner
暴胀解决了宇宙学中的大多数基本问题-平坦性的起源，大尺度平滑性，以及今天宇宙中所看到的所有结构所需的小密度不均匀性。如果是正确的，它将把我们对宇宙的理解扩展到10 - 32秒，并打开一扇10 - 15 GeV能量的物理学窗口。然而，目前几乎没有证据证实或反驳通货膨胀，也没有标准的通货膨胀模型。检验暴胀的关键是关注它的三个基本预言[1]：空间平坦的宇宙（总能量密度等于临界能量密度）;高斯密度扰动的几乎标度不变谱[2];随机引力波的几乎标度不变谱[3]。前两个预言有重要的意义：非重子暗物质的存在，因为大爆炸核合成阻止重子贡献超过临界密度的10%[4]，以及冷暗物质的结构形成，基于非重子暗物质是从最早时刻遗留下来的缓慢移动的基本粒子的想法[5，6]。大量的宇宙学观测现在开始对前两个预言进行严格的检验[6]。引力波是暴胀的有力检验和探测：它们提供了一致性检验（见下文）;它们对于了解驱动暴胀的标量势是必不可少的[7];它们是暴胀的一个令人信服的特征--在暴胀之前，人们都主张宇宙是平坦的，密度扰动是标度不变的。探测暴胀产生的重力波是一个巨大的实验挑战[8]。在这封信中，我们讨论了CBR各向异性或偏振的潜力，以及激光干涉仪直接检测的潜力，以检验这一关键的暴胀预测。暴胀期间激发的度规涨落的傅立叶谱的特征是波数k的幂律，对于密度扰动（标量度规涨落）为k n，对于重力波（张量度规涨落）为k nT − 3。密度扰动的尺度不变性（n = 1）对应于牛顿势的波动，与波数无关;重力波的尺度不变性（nT = 0）对应于无量纲的水平交叉应变振幅，与波数无关。幂律指数与驱动暴胀的标量场势V（？）有关：n − 1 = − m 2
Introduction Inflation addresses most of the fundamental problems in cosmology – the origin of the flatness, large-scale smoothness, and small density inhomogeneities needed to seed all the structure seen in the Universe today. If correct, it would extend our understanding of the Universe to as early as 10 −32 sec and open a window on physics at energies of order 10 15 GeV. However, at the moment there is little evidence to confirm or to contradict inflation and no standard model of inflation. The key to testing inflation is to focus on its three basic predictions [1]: spatially flat Universe (total energy density equal to the critical energy density); almost scaleinvariant spectrum of gaussian density perturbations [2]; and almost scale-invariant spectrum of stochastic gravitational waves [3]. The first two predictions have important implications: the existence of nonbaryonic dark matter, as big-bang nucleosynthesis precludes baryons from contribution more than about 10% of the critical density [4], and the cold dark matter scenario for structure formation, based upon the idea that the nonbaryonic dark matter is slowly moving elementary particles left over from the earliest moments [5,6]. A host of cosmological observations are now beginning to sharply test the first two predictions [6]. Gravity waves are a telling test and probe of inflation: They provide a consistency check (see below); they are essential to learning about the scalar potential that drives inflation [7]; and they are a compelling signature of inflation – both a flat Universe and scale-invariant density perturbations were advocated before inflation. Detecting inflation-produced gravity waves presents a great experimental challenge [8]. In this Letter we discuss the potential of CBR anisotropy or polarization and of direct detection by the laser-interferometers to test this key prediction of inflation. Quantum Fluctuations The (Fourier) spectra of metric fluctuations excited during inflation are characterized by power laws in wavenumber k, k n for density perturbations (scalar metric fluctuations) and k nT −3 for gravity waves (tensor metric fluctuations). Scale invariance for density perturbations (n = 1) corresponds to fluctuations in the Newtonian potential that are independent of wavenumber; scale invariance for gravity waves (nT = 0) corresponds to dimensionless horizon-crossing strain amplitudes that are independent of wavenumber. The power-law indices are related to the scalar field potential, V (�), that drives inflation: n − 1 = − m 2