AI 中文总结
研究宇宙黎明时期21厘米观测中声学振荡，提出分解21厘米功率谱方法，发现BAO和VAO形状有百分比级偏移及校正，展示其演化对早期星系和恒星物理的敏感性，预测SKA敏感度，为宇宙膨胀和首批恒星研究提供有力约束。
AI 中文摘要
宇宙黎明时期的21厘米观测将把标准尺宇宙学扩展到最初的十亿年，揭示宇宙微波背景和大尺度结构无法触及的时代。要实现这一目标，需要一个精确的早期恒星形成声学结构模型。在早期，物质过密度和冷暗物质与重子之间的流速度这两种相互平衡的现象调节着恒星形成的空间统计。过密度决定早期星系晕的形成位置，而高速区域抑制恒星形成。它们对星系间介质的综合影响产生了具有重子声学振荡（BAO）和速度诱导声学振荡（VAO）的21厘米波动。本文提出了将21厘米功率谱分解为其组成声学特征的首个方法。发现BAO和VAO形状之间存在百分比级别的偏移，若在标准尺分析中忽略，会使推断的哈勃常数\(H(z)\)值产生约2%的偏差，并提供了校正。此外，随着BAO和VAO的相对突出程度在宇宙黎明时期非单调地起伏，展示了它们的演化对早期星系演化和首批恒星物理的敏感性。最后，预测了平方公里阵列（SKA）对BAO-VAO组合标准尺的敏感度。结果表明联合BAO-VAO建模是21厘米声学推断的重要组成部分，能够对宇宙膨胀和首批恒星进行有力约束。
英文摘要
Cosmic dawn 21-cm observations will extend standard-ruler cosmology into the first billion years, unlocking epochs inaccessible by the cosmic microwave background and large-scale structure. Realizing this promise requires an accurate model of the acoustic structure imprinted onto early star formation. At such early times, two counterbalancing phenomena -- matter overdensities and streaming velocities between cold dark matter and baryons -- modulate the spatial statistics of star formation. While overdensities dictate where early galaxy-bearing haloes form, regions of high velocity suppress star formation. Their combined influence on the intergalactic medium yields 21-cm fluctuations with both baryon (BAO) and velocity-induced (VAO) acoustic oscillations. Here we present the first prescription to decompose the 21-cm power spectrum into its constituent acoustic features. We find a percent-level offset between the BAO and VAO shapes which, if ignored in standard-ruler analyses, would bias inferred values of $H(z)$ by $\sim 2\%$; we provide a correction. Moreover, as the relative prominence of BAOs and VAOs ebbs and flows non-monotonically across cosmic dawn, we demonstrate how their evolution is sensitive to the physics of early galaxy evolution and the first stars. Finally, we forecast how sensitive SKA will be to the BAO-VAO combined standard ruler. Our results establish joint BAO-VAO modeling as an essential ingredient of 21-cm acoustic inference, enabling robust constraints on both cosmic expansion and the first stars.
Comments5+7 pages, 3+1 figures
