Probing Cosmology with Diffuse Background Radiation Observations

用漫反射背景辐射观测探测宇宙学

• 批准号: RGPIN-2022-05216
• 负责人: Hinshaw, Gary
• 金额: $ 2.99万
• 依托单位: University of British Columbia
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=763001
• 关键词: Probing; Cosmology; Diffuse; Background; Radiation

The long--term objective of my research program is to understand the origin and evolution of the universe, and to shed light on the physics of dark matter and dark energy. In collaboration with a number of other astrophysics researchers, I design, build, and operate special purpose telescopes that collect radio and microwave signals from our own galaxy - the Milky Way - and from more distant sources, some as far away as the edge of the observable universe. The data we collect comprises a valuable fossil record of conditions in the younger universe, and help us tease out how the universe formed and evolved. Existing cosmological observations have pointed to the existence of dark matter: a form of matter which does not occupy the Periodic Table of the elements; and to dark energy, which could be energy associated with the vacuum of free space itself, as posited by quantum theory. The bulk of my proposed research effort is devoted to building and operating two new telescopes: the Canadian Hydrogen Intensity Mapping Experiment (CHIME), and the Canadian Galactic Emission Mapper (CGEM), both of which are or will be located at the Dominion Radio Astrophysical Observatory, located just south of Penticton British Columbia. CHIME is a novel and complex radio telescope comprised of 4 co-linear cylindrical reflectors with 2048 receiving elements. Its primary goal is to characterize dark energy by measuring the expansion history of the universe in the redshift range z=0.8-2.5, when the universe was roughly half its present age. CHIME recently detected cosmological 21 cm emission in cross correlation with data from the Sloan Digital Sky Survey, an important milestone in the path to characterizing the dark energy. Continuing the analysis of CHIME data is a major element of my proposed research. CGEM is to be a nimble 4-metre scanning telescope which will survey the northern sky at a frequency of ~10 GHz to map polarized synchrotron emission in the Milky Way. This signal is an important source of foreground confusion for cosmic microwave background (CMB) experiments that are searching for evidence of primordial gravitational waves produced a fraction of a second after the Big Bang, by a hypothesized period of cosmic inflation. If present, the gravity wave background would produce a curl-like pattern in the CMB polarization, but existing upper limits on such a signal already indicate that it will be foreground dominated at all frequencies, hence it is crucially important to have well-characterized foreground measurements over a range of frequencies spanning the CMB frequency "window" in order to disentangle the CMB and foreground signals. This pair of relatively small astrophysics projects are akin to "tabletop" experiments in laboratory physics. Designed and purpose built in-house, but with very high-profile science goals, they attract very talented HQP and serve as ideal training grounds for students seeking to become well-rounded scientists.

我的研究计划的长期目标是了解宇宙的起源和演化，并阐明暗物质和暗能量的物理学。我与其他一些天体物理学研究人员合作，设计、建造和操作特殊用途的望远镜，收集来自我们自己的星系——银河系——和更遥远的来源的无线电和微波信号，有些远到可观测宇宙的边缘。我们收集的数据包括年轻宇宙条件的宝贵化石记录，并帮助我们梳理宇宙是如何形成和演化的。现有的宇宙学观测已经指出了暗物质的存在：一种不占据元素周期表的物质形式；暗能量，也就是量子理论所假定的，与自由空间本身的真空有关的能量。我提议的大部分研究工作致力于建造和运行两个新望远镜：加拿大氢强度测绘实验（CHIME）和加拿大银河发射测绘仪（CGEM），这两个望远镜都位于或将位于不列颠哥伦比亚省彭蒂克顿以南的道明射电天体物理天文台。CHIME是一种新型的复杂射电望远镜，由4个共线圆柱形反射镜和2048个接收单元组成。它的主要目标是通过测量宇宙在红移范围z=0.8-2.5的膨胀历史来表征暗能量，当时宇宙大约是现在年龄的一半。CHIME最近探测到21厘米的宇宙辐射，与斯隆数字巡天的数据相互关联，这是表征暗能量道路上的一个重要里程碑。继续分析CHIME数据是我提出的研究的主要内容。CGEM将是一个灵活的4米扫描望远镜，它将以~10千兆赫的频率调查北方天空，绘制银河系的偏振同步辐射图。这个信号是宇宙微波背景（CMB）实验前景混乱的一个重要来源，这些实验正在寻找宇宙大爆炸后不到一秒产生的原始引力波的证据，这是一个假设的宇宙膨胀时期。如果重力波背景存在，它将在CMB极化中产生一个卷状图案，但现有的这种信号的上限已经表明，它将在所有频率上占前景主导地位，因此，在跨越CMB频率“窗口”的频率范围内进行特征良好的前景测量，以解开CMB和前景信号的纠缠至关重要。这两个相对较小的天体物理学项目类似于实验室物理学中的“桌面”实验。它们是内部设计和专门建造的，但具有非常高调的科学目标，吸引了非常有才华的HQP，并为寻求成为全面发展的科学家的学生提供了理想的训练基地。