透过最后散射面之纱：利用CMB谱畸变观测宇宙

中文摘要 AI 辅助

宇宙微波背景辐射的频谱是自然界中测量到的最精确的黑体辐射，COBE卫星将其偏离约束在接近百万分之一的水平。然而，在标准ΛCDM宇宙学中，偏离完美黑体的畸变确实存在，它们潜伏在我们当前观测界限的表面之下。这些谱畸变提供了关于复合前后两个时期热历史的宝贵信息，使我们能够窥探最后散射面之外，进入原初宇宙。在此，我们概述了在各个时期产生CMB谱畸变的基础物理。作为这一丰富物理的例证，我们回顾了一系列能够在标准ΛCDM框架内外产生畸变的机制。我们还讨论了超越单极（天空平均）谱并利用各向异性谱畸变中的空间信息所能获取的信息。为了补充我们对谱畸变多样科学的讨论，我们概述了即将到来和拟议中的实验布局。我们强调，TMS、COSMO和BISOU实验的组合将在未来十年内首次发现单极y型畸变。从太空来看，拟议的FOSSIL实验预计将比原始的COBE/FIRAS测量灵敏度提高约三个数量级，从而探测到由复合前等离子体中小尺度声学模式耗散产生的ΛCDM μ型畸变。随着变革性测量的临近，CMB谱畸变为红移z ≲ 2×10^6的宇宙热历史提供了独特灵敏的探针。

英文摘要

The frequency spectrum of the cosmic microwave background is the most precise blackbody ever measured in nature, with deviations constrained at the level of almost one part per million from the COBE satellite. Nevertheless, departures away from a perfect blackbody are present in standard $Λ$CDM cosmology, lurking just beneath the surface of our current observational bounds. These spectral distortions provide invaluable information on our thermal history in both the post- and pre-recombination epochs, allowing us to peer beyond last scattering and into the primordial Universe. Here, we present an overview of the underlying physics responsible for generating CMB spectral distortions at all epochs. As an illustration of this rich physics, we review a comprehensive set of mechanisms capable of generating distortions both within and beyond the standard $Λ$CDM paradigm. We also discuss the information that can be gleaned by going beyond the monopole (sky-averaged) spectrum and exploiting the spatial information present in anisotropic spectral distortions. To supplement our discussion of the diverse science of spectral distortions, we provide an overview of the upcoming and proposed experimental landscape. We highlight that the combination of the TMS, COSMO, and BISOU experiments will provide the first discovery of a monopole $y$-type distortion within the coming decade. From space, the proposed FOSSIL experiment is forecasted to improve upon the original COBE/FIRAS measurement by roughly three orders of magnitude in sensitivity, bringing with it the detection of the $Λ$CDM $μ$-type distortion sourced by the dissipation of small scale acoustic modes in the pre-recombination plasma. With transformational measurements on the horizon, CMB spectral distortions offer a uniquely sensitive probe of the thermal history of the Universe at redshifts $z \lesssim 2 \times 10^6$.

发表机构

• Massachusetts Institute of Technology（麻省理工学院）
• Université Paris-Saclay, CNRS, Institut d’Astrophysique Spatiale（巴黎萨克雷大学，法国国家科学研究中心，天体物理研究所）
• Boston University（波士顿大学）
• Sapienza Universitá di Roma（罗马第一大学）
• INFN, Sezione di Roma（意大利国家核物理研究所，罗马分部）
• University of Manchester（曼彻斯特大学）
• Instituto de Física de Cantabria (IFCA), CSIC-Univ. de Cantabria（坎塔布里亚物理研究所，西班牙高等科学研究委员会-坎塔布里亚大学）
• Jodrell Bank Centre for Astrophysics（乔德雷尔银行天体物理学中心）
• University of Oxford（牛津大学）
• University of Sheffield（谢菲尔德大学）
• Leibniz University Hannover（汉诺威莱布尼茨大学）
• Max Planck Institute for G（马克斯·普朗克G研究所）

机构由 AI 辅助整理，请以论文原文为准。