Research in Theoretical Astronomy 2009-2014

剑桥大学天文学研究所是世界领先的天文学研究机构之一。它包括19名学术人员，51名博士后研究助理和52名博士生，其中约一半从事理论天文学工作。本拨款申请要求延长IoA的主要理论滚动拨款。在接下来的五年里，我们将对以下问题进行广泛的理论研究：(i)普朗克卫星是第三代空间卫星，专门用于测量宇宙微波背景中的温度和极化各向异性。普朗克计划在2008年底发射，这距离欧空局首次提出这个计划已经过去了15年。这笔拨款涵盖的年份与这颗卫星科学开发的高峰期相吻合。要求PDRA支持与共同调查员在核心科学项目上合作。特别是，我们负责领导对普朗克宇宙参数的关键分析，并希望研究宇宙膨胀模型的约束条件。剑桥大学在三叶草极化实验中起着主导作用我们希望PDRAs参与到实验的科学解释中来。（ii）宇宙微波背景辐射为我们提供了40万年前的宇宙图景。那时，宇宙充满了氢、氦、暗物质和辐射的近乎均匀的混合物。我们将研究第一个非线性结构是如何从这个随机背景中出现的。在拨款期间，研究的主要重点将是进行流体动力学模拟，包括辐射转移，以模拟星系间介质的热状态和空间扩展的Lyalpha发射。我们还将扩展先前在Ly α森林的物质功率谱上的工作，结合普朗克的数据来约束中微子的质量。大量系外行星的发现使人们对行星形成的理论工作产生了极大的兴趣。在拨款期间，我们将继续开展一项研究计划，建立在原行星和碎片盘演化方面的专业知识基础上。这项工作将集中在连接原行星阶段，当圆盘富含气体，可能是正在形成的气体行星的地点，到碎片盘阶段，当圆盘是气体贫乏的，尘埃结构，小行星带可能是类地行星形成的地点。吸积盘存在于各种各样的天文系统中。特别是，致密物体（如黑洞、中子星和白矮星）上的吸积产生的观测特征，为x射线卫星和引力波探测器提供了主要的科学依据。磁场是理解吸积盘演化的核心。我们将对磁化吸积盘进行最先进的数值模拟，以了解它们在吸积盘动力学中的作用，并计算观测特征。(v)了解恒星演化对于解释所有天体物理系统，从我们银河系的恒星到宇宙中第一个非线性结构的形成，都是必不可少的。在接下来的五年里，我们将开发改进的大质量恒星模型，作为超新星和伽马射线暴的祖先。我们还将与利弗莫尔的同事合作，开发双星系统中恒星演化的全三维数值模型。（vi）最后，我们将进行两个研究主题，以了解星系团核心的反馈过程。我们将研究“发射线细丝”的物理学，它仍然不被理解，我们将使用大型数值模拟来评估重子物理学对使用星系团作为宇宙探测器的影响（例如测试暗能量的性质）。

The Institute of Astronomy, Cambridge, is one of the worlds leading research Institutes in Astronomy. It comprises 19 academic staff, 51 postdoctoral research assistants and 52 PhD students, about half of whom work on theoretical astronomy. This grant application is asking for a renewal of the main theoretical rolling grant at the IoA. Over the next five years we will pursue a broad range of theoretical research on the following problems: (i) The Planck satellite is a third generation space satellite dedicated to measuring the temperature and polarization anisotropies in the cosmic microwave background. Planck is scheduled for launch at the end of 2008, some 15 years after it was first proposed to ESA. The years covered by the grant coincide with the peak period for the scientific exploitation of this satellite. PDRA support is requested to work with the Co-Investigators on core science projects. In particular, we are responsible for leading the key analysis of cosmological parameters from Planck and wish to investigate constraints on models of cosmic inflation. Cambridge has a leading role in the Clover polarization experiment and we wish to involve PDRAs in the scientific interpretation of that experiment. (ii) The cosmic microwave background radiation provides us with a picture of the Universe when it was 400,000 years old. At that time, the Universe was filled with a near uniform mixture of hydrogen , helium, dark matter and radiation. We will investigate how the first non-linear structures emerged from this stochastic background. Over the grant period the main emphasis of the research will be to perform hydrodynamic simulations including radiative transfer to model the thermal state of the intergalactic medium and spatially extended Lyalpha emission. We will also extend previous work on the matter power spectrum from the Ly alpha forest to constrain neutrino masses, in combination with data from Planck. (iii) The discovery of large numbers of extrasolar planets has led to enormous interest in theoretical work on the formation of planets. Over the grant period we will pursue a research programme building on expertise in protoplanetary and debris disk evolution. The work will be centred on linking the protoplanetary phase, when discs were gas rich and possible sites of ongoing gaseous planet formation, through to the debris disc phase, when discs were gas poor, dusty structures, with planetesimal bels as possible sites for terrestrial planet formation. (iv) Accretion discs are present in a wide variety of astronomical systems . In particular, accretion onto compact objects such as black holes, neutron stars and white dwarfs produce observational signatures that provide the main scientific justification for X-ray satellites and gravitational wave detectors. Magnetic fields are central to understanding the evolution of accretion discs. We will perform state-of-the-art numerical simulations of magnetised accretion discs to understand their role in accretion disc dynamics and to compute observational signatures. (v) Understanding stellar evolution is essential for the interpretation of all astrophysical systems, from stars in our own Galaxy to the formation of the first non-linear structures in the Universe. Over the next five years we will develop improved models of massive stars as the progenitors of supernovae and gamma-ray bursts. We will also develop fully three-dimensional numerical models of stellar evolution in binary systems, in collaboration with colleagues at Livermore. (vi) Finally, we will pursue two research themes to understand feedback processes in the cores of clusters of galaxies. We will investigate the physics of `emission line filaments', which are still not understood and we will use large numerical simulations to assess the impact of baryonic physics on the use of clusters as cosmological probes (e.g. testing the nature of dark energy.