Constraining Bias via Clustering in Galaxy Surveys

AST0206243 Szapudi目前的宇宙学理论表明，我们可以看到的恒星、星系和星系团只占宇宙物质含量的相对较小的一部分。大多数物质都是我们未知的形式，只有通过它的引力才能被探测到。这种“暗物质”的性质是当代理论物理学中最有趣的一个问题，它的研究涉及不同学科的信息融合，如粒子物理、天文学和宇宙学。这个项目的目的是通过观察可见物质和暗物质的统计性质之间的差异来限制这种难以捉摸的暗物质的性质。根据目前的结构形成理论，早期宇宙中的小初始波动在引力的影响下增长，直到我们今天看到的大规模结构形成。星系似乎是在下面的暗物质集中成团块(称为晕)的地方形成的。因此，目前星系的分布既取决于暗物质的分布，也取决于暗物质晕变成星系的效率。Szapudi博士和他的合作者开发的新的统计方法将被用来描述星系的当今分布，使用来自正在进行的广泛领域调查(例如，斯隆数字天空调查)的数据，这些调查涵盖了多达100万个天体。然后，偏差理论将被应用于这些测量的分布，以限制底层暗物质的分布。反过来，这种分布可以用来检验各种现象学和基础理论中的预测，这些理论已经被开发来描述“暗物质”。

AST 0206243SzapudiCurrent cosmological theories imply that the stars, galaxies and clusters of galaxies that we can see represent only a relatively small fraction of the matter content of the universe. Most of the matter is in a form unknown to us, and can be detected only through its gravitational pull. The nature of this ``Dark Matter'' is the single most interesting problem in contemporary theoretical physics, and its study involves the amalgamation of information from different disciplines, such as particle physics, astronomy, and cosmology. The present project aims to constrain the properties of this elusive dark matter by looking at ``bias'', the difference between the statistical properties of visible and dark matter.According to current theories of structure formation, small initial fluctuations in the early Universe grew under the influence of gravity until the large-scale structures which, we see at the present day, formed. It appears that galaxies formed where the underlying dark matter concentrated in clumps (called halos). Thus, the present distribution of galaxies depends both on the distribution of dark matter and on the efficiency with which dark matter halos turn into galaxies. Novel statistical measures developed by Dr. Szapudi and his collaborators will be used to characterize the present-day distribution of galaxies using data from on-going wide field surveys (e.g., the Sloan Digital Sky Survey) which encompass up to a million objects. Then the theory of bias will be applied to these measured distributions to constrain the distribution of the underlying dark matter. This distribution, in turn can be used to test predictions from the various phenomenological and fundamental theories which have been developed to describe the "Dark Matter".***