Topics in Early Universe Cosmology

探索我们宇宙结构的新的观测窗口正在打开。高精度的小角尺度微波各向异性图目前正在为我们提供有关早期宇宙的令人兴奋的信息，而包含更多信息的微波偏振图将很快出现。新的望远镜即将上线，它将绘制出高红移星系的分布，观测宇宙学家正在制定计划，对宇宙进行21厘米的红移测量，这将确定重子物质的分布，甚至在恒星形成开始之前。我研究的一个中心主题是研究我们可以从这些关于基础物理的新调查中学到什么。早期宇宙的快速膨胀提供了一种显微镜，它可以延伸到可见尺度，长度尺度在非常早期的宇宙中对应的能量尺度甚至比在最高能量的地面加速器上探测的能量尺度要高得多。在一项研究中，我的团队将在上述新的观测窗口中搜索宇宙弦(量子场论中的拓扑缺陷，类似于晶体中的线缺陷)的签名。目前，宇宙学观测可以用早期宇宙的一个标准范例很好地解释，即所谓的暴涨“Lambda CDM”情景。对这一模式进行进一步检查是很重要的。此外，这一情景虽然在现象上是成功的，但也存在一些概念性问题。在第二条研究路线中，我们将考虑通胀情景的替代方案，如弦气体宇宙论或“弹跳宇宙”范式。我们将试图找到这些情景的更好实现，并制定出新的预测，以将它们与通胀情景区分开来。我研究的第三个主题将是暗能量，这是一种神秘的成分，目前占宇宙能量的三分之二以上。

New observational windows to probe the structure of our universe are opening up. High accuracy small angular scale microwave anisotropy maps are currently providing us with exciting information about the early universe, and microwave polarization maps which contain even more information will soon be available. New telescopes are coming online which will map out the distribution of galaxies at high redshifts, and observational cosmologists are working on plans for 21cm redshift surveys of the universe which will determine the distribution of baryonic matter even before the onset of star formation. A central theme of my research is to study what we can learn from these new surveys about fundamental physics. The rapid expansion of the early universe provides a microscope which stretches to visible scales length scales which in the very early universe correspond to energy scales much higher even than those explored at the highest energy terrestrial accelerators. In one line of research, my team will search for signatures of cosmic strings (topological defects in quantum field theories which are analogous to line defects in crystals) in the above-mentioned new observational windows. Currently, cosmological observations can be well explained by a standard paradigm of the early universe, namely the so-called inflationary "Lambda CDM" scenario. It is important to develop further checks of this model. Also, this scenario, although phenomenologically successful, suffers from a number of conceptual problems. In a second line of research we will consider alternatives to the inflationary scenario such as string gas cosmology or the "bouncing universe" paradigm. We will attempt to find improved realizations of these scenarios and work out new predictions with which they can be distinguished from the inflationary scenario. A third theme of my research will be on dark energy, the mysterious component which currently makes up more than two thirds of the energy of the universe.