RUI: Statistical Modeling of Microlens Masses

RUI：微透镜质量的统计建模

• 批准号: 0205754
• 负责人: William Heacox
• 金额: $ 3.49万
• 依托单位: University of Hawaii at Hilo
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-08-01 至 2005-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0205754&HistoricalAwards=false
• 关键词: RUI; Statistical; Modeling; Microlens; Masses

AST-0205754HeacoxDr. William Heacox will analyze gravitational microlens survey data in the current literature in order to deduce the mass distributions of the objects causing the lensing, and thus help characterize their natures. Microlensing is a promising means of detecting otherwise undetectable planetary- to stellar-mass objects in such locations as the halo of our galaxy, where a large amount of dark matter of unknown nature is known to exist. In a typical microlens survey, a few million stars in the Large Magellanic Cloud are monitored periodically to detect the optical amplification caused by gravitational lensing when a Galactic halo object (the lens) passes nearly in front of a background star (the source). While the resulting amplification amplitude depends upon lens mass, it also depends upon such unknowable quantities as the relative velocity of lens and source, and the distance of closest encounter of the lens to the line-of-sight to the source. This complication has prevented accurate estimates of lens masses, so that the observation of a few tens of microlenses has not greatly aided in the identification of halo dark matter. Dr. Heacox' research consists of the application of sophisticated statistical modeling techniques to the entire set of observed microlenses in a survey, in order to determine the statistical distribution of lens masses (rather than the masses of individual lenses). The method uses all that is knowable about the kinematics (velocities, distances) of lens and source populations, together with the set of observed microlens parameters, to infer all that can be deduced about the mass distribution of the underlying population causing the lensing. In application to the Galactic halo microlenses, the result should be the first credible estimate of the mass distribution of the halo dark matter, and a concomitant increase in our understanding of the nature of this material. The nature of dark matter in the Universe is one of the outstanding problems in modern astronomy; a better understanding of the component in our galaxy will be a useful first step in determining what most of the Universe is made of. This award is made under the auspices of the Research in Undergraduate Institutions (RUI) program at NSF.***

AST-0205754 HeacoxDR.威廉·希科克斯将分析目前文献中的引力微透镜测量数据，以推断导致透镜的物体的质量分布，从而帮助描述它们的性质。微透镜是一种很有希望的方法，可以在我们银河系的光晕等位置探测到原本无法探测到的行星到恒星质量的物体，已知那里存在大量未知性质的暗物质。在典型的微透镜测量中，大麦哲伦星云中的数百万颗恒星被定期监测，以检测当银河晕物体(透镜)几乎从背景恒星(源)前面经过时，引力透镜引起的光学放大。虽然由此产生的放大幅度取决于透镜的质量，但它也取决于诸如透镜和光源的相对速度，以及透镜到光源的视线最近相遇的距离等不可知的量。这种复杂性阻碍了对透镜质量的准确估计，因此，对几十个微透镜的观察对识别晕暗物质没有太大帮助。希科克斯博士的研究包括将复杂的统计建模技术应用于调查中观察到的整套微透镜，以确定镜片质量(而不是单个镜片的质量)的统计分布。该方法使用关于透镜和源群体的运动学(速度、距离)的所有已知信息，以及一组观察到的微透镜参数，来推断关于引起透镜的底层群体的质量分布的所有可以推断的信息。在应用于银河晕微透镜时，结果应该是对晕暗物质质量分布的第一个可信估计，以及随之而来的对这种材料性质的理解的增加。宇宙中暗物质的性质是现代天文学中的突出问题之一；更好地了解我们银河系的成分将是确定宇宙大部分组成的有用的第一步。该奖项由美国国家科学基金会本科生研究计划(RUI)赞助。*