Experimental radio cosmology at Oxford

在过去的15年里，由于探测到宇宙微波背景(CMB)中的涨落，我们对宇宙的理解发生了变化。这些波动是由于原始宇宙流体密度的微小变化造成的，当时宇宙只有一秒钟的极小部分。宇宙以极快的速度膨胀，持续了不到一秒的时间，这种现象被天文学家称为“膨胀”。已经建造了大量仪器，通过测量这些各向异性的大小作为角度尺度(它们的“功率谱”)的函数来表征它们的空间分布。这些测量非常重要，因为它们告诉了我们很多关于宇宙演化的信息，而且因为各向异性包含了导致宇宙目前结构的代码。牛津大学实验宇宙学小组的成员在CAT、VSA和CBI等宇宙学仪器方面发挥了主导作用。这些仪器和其他仪器，最著名的是NASA太空望远镜WMAP，揭示了大量令人难以置信的准确信息，例如，宇宙具有平面几何结构，其年龄为137亿年，宇宙中94%的物质并不是我们所知的物质，而是一种新形式的物质--暗物质，以及一种更神秘的暗能量形式的组合。那么，这就是故事的结尾吗？相反，我们在过去15年中获得的知识促使我们去寻找物理学和天文学中更基本的问题的答案。暗物质是一个谜，因为我们不能直接探测到它，但我们至少可以清楚地观察到它的引力影响。然而，暗能量要奇怪得多，因为它会导致宇宙的膨胀加速，而不是减速。这真的是真的吗？或者有没有另一种解释来调和我们所有的观察？我们能明确地确认通胀确实发生了吗？如果是的话，通胀的能源规模是多少？这些都是下一代宇宙学仪器面临的挑战，这笔STFC赠款将使牛津大学为这些令人兴奋的发展做出重大贡献。我们的工作将以几种方式提供给下一步的宇宙学发展。我们参与了新的国家和国际宇宙学项目，这些项目的目标是比以往建造的任何仪器的灵敏度高10倍。这些仪器将能够探测到极弱的信号，如CMB偏振，它包含的信息与CMB各向异性一样多，从而使我们能够构建宇宙演化的完整图景。我们的团队包括天文学家，他们是仪器设计和建造方面的专家，也是观测和数据分析方面的专家。我们还建造了自己的小型仪器来调查提供给总体情况的特定效应，最后我们发展了支持上述活动的技术和天体物理基础研究。我们在此应用程序中请求的支持直接属于这些类别。我们请求为博士后研究科学家提供支持，以分析我们正在努力建造的仪器将产生的天文数据。我们还要求帮助我们开发制造这些仪器所需的最先进的技术，最后，我们要求提供硬件，使我们能够在我们的实验室开发和测试这项技术。这是一个令人兴奋的计划，利用聪明的年轻科学家的巨大潜力，将理论、天文观测和实验物理联系起来，帮助我们了解我们周围的世界。

Our understanding of the universe has been transformed over the past 15 years as a result of the detection of the fluctuations in the Cosmic Microwave Background (CMB). These fluctuations result from tiny variations in the density of the primordial cosmic fluid when the universe was a tiny fraction of a second old. These were blown up to astronomical size by an extremely rapid expansion of the universe which lasted a minute fraction of a second; a phenomenon that astronomers call 'inflation'. A large number of instruments have been built to characterize the spatial distribution of these anisotropies by measuring their magnitude as a function of angular scale (their `power spectrum'). These measurements are very important because they tell us a lot about the evolution of the universe and because the anisotropies contain the code the led to the present structure in the universe. Members of the Experimental Cosmology group at Oxford have taken a leading role in cosmology instruments such as CAT, VSA and CBI. These instruments, and others, most notably the NASA space telescope WMAP, have revealed an incredible amount of accurate information, such as that the universe has a flat geometry, its age is 13.7 billion years and that 94% of the substance in the universe is not matter as we know it, but is a combination of a new form of matter called 'dark matter', and an even more mysterious form of dark energy. Is this then the end of the story then? On the contrary, the knowledge we have gained in the last 15 years induces us to seek answers to even more fundamental questions in physics and astronomy. Dark matter is a puzzle since we cannot detect it directly, but we can at least observe its gravitational impact clearly. Dark energy however is a lot more bizarre since it causes the expansion of the universe to accelerate rather than to slow down. Is this really true or is there an alternative explanation that reconciles all our observations? Can we confirm categorically that inflation really occurred and if so at what energy scale? These are the challenges of the next generation of cosmology instruments and this STFC grant will allow Oxford to make major contributions to these exciting developments. Our work will feed into the next cosmology developments in several ways. We take part in new national and international cosmology projects that are aiming to be 10 times more sensitive than any instrument ever built. These instruments will be able to detect extremely weak signals such as the CMB polarization that hold as much information as the CMB anisotropies, thereby allowing us to build a complete picture of the evolution of the universe. Our team includes astronomers who are experts in instrument design and construction and also in observation and data analysis. We also build our own small-scale instrument to investigate specific effects that feed into the general picture, and finally we develop the basic research in technology and astrophysics that supports the above mentioned activities. The support that we have requested in this application falls directly into these categories. We requested support for post-doctoral research scientists to analyse the astronomical data that will stream from instruments that we are working hard to build. We are also asking for effort to help us develop the state of the art technology that is required for building these instruments and finally we are asking for the hardware that will allow us develop and test this technology in our laboratories. It is an exciting programme that links theory, astronomical observation and experimental physics using the tremendous potential of bright young scientist to help us understand the world around us.