Experimental radio cosmology at Oxford

在过去的15年里，由于探测到宇宙微波背景（CMB）的波动，我们对宇宙的理解已经发生了变化。这些波动是由于宇宙诞生不到一秒时原始宇宙流体密度的微小变化造成的。由于宇宙持续了几分之一秒的极快膨胀，它们被膨胀到天文数字的大小；这种现象被天文学家称为“暴胀”。已经建立了大量的仪器，通过测量它们的大小作为角尺度的函数（它们的“功率谱”）来表征这些各向异性的空间分布。这些测量非常重要，因为它们告诉我们很多关于宇宙演化的信息，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等宇宙学仪器中发挥了主导作用。这些仪器和其他仪器，最著名的是美国宇航局太空望远镜WMAP，已经揭示了大量令人难以置信的准确信息，比如宇宙具有平坦的几何形状，它的年龄为137亿年，宇宙中94%的物质不是我们所知道的物质，而是一种名为“暗物质”的新物质形式的组合，还有一种更神秘的暗能量形式。这就是故事的结局了吗？相反，我们在过去15年中获得的知识促使我们寻求物理学和天文学中更基本问题的答案。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，因为它使宇宙的膨胀加速而不是减缓。这是真的吗？还是有另一种解释可以调和我们所有的观察结果？我们能否明确确认暴胀确实发生过，如果是的话，在什么能量尺度上？这些都是下一代宇宙学仪器的挑战，这项STFC资助将使牛津大学为这些令人兴奋的发展做出重大贡献。我们的工作将在几个方面为下一个宇宙学的发展提供帮助。我们参与了新的国家和国际宇宙学项目，这些项目的目标是将灵敏度提高到以往任何仪器的10倍。这些仪器将能够探测到极其微弱的信号，比如CMB的极化信号，这种信号与CMB的各向异性信息一样多，从而使我们能够建立一幅宇宙演化的完整图景。我们的团队包括天文学家，他们是仪器设计和构造方面的专家，也是观测和数据分析方面的专家。我们还建立了自己的小型仪器来研究对总体情况有影响的特定影响，最后我们发展了支持上述活动的技术和天体物理学的基础研究。我们在此应用程序中请求的支持直接属于这些类别。我们请求支持博士后研究科学家分析来自我们正在努力建造的仪器的天文数据。我们还要求努力帮助我们开发制造这些仪器所需的最先进技术，最后我们还要求提供硬件，使我们能够在实验室中开发和测试这项技术。这是一个令人兴奋的项目，它将理论、天文观测和实验物理学联系起来，利用聪明的年轻科学家的巨大潜力，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.