Binary Lenses: The Power of Two

二元透镜：两个的力量

• 批准号: 0708924
• 负责人: Rosanne Di Stefano
• 金额: $ 36.52万
• 依托单位: Smithsonian Institution Astrophysical Observatory
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-15 至 2010-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0708924&HistoricalAwards=false
• 关键词: Binary; Lenses; Power; Two

This project is concerned with interpreting the signals of gravitational microlensing events in searches for Massive Compact Halo Objects (MACHOs) in the halo of the Milky Way. If a significant fraction of halo dark matter consists of MACHOs, monitoring programs should discover more microlensing events than can be generated by known stellar populations. More than 2500 microlensing events have been discovered during the past 15 years. The present rate of discovery is roughly 600 per year, and will soon increase as new monitoring programs begin. Most light curves are of the standard point-source, point-lens type. These "vanilla" light curves are highly degenerate: in the absence of clear parallax effects, only a combination of the lens mass, speed, and position can be estimated. To determine the contribution associated with MACHOs, one must therefore rely on statistical studies. Although results from the first generation of monitoring programs place limits on the MACHO fraction, the results are still highly uncertain.Binary lens light curves, on the other hand, contain more information. Under ideal circumstances the position, speed, and mass of the lens can be measured, and limits can be placed on the binary's orbital separation and mass ratio. Binary lenses can therefore provide powerful diagnostics. Those located in the source galaxy can potentially be identified and appropriately subtracted from the signature of dark masses in the Halo. Binary MACHOs(if they exist) can be identified, and the wealth of information coded in binary-lens light curves presents the exciting prospect of measuring the properties of individual MACHOs.The power gained through studying individual events is magnified for an ensemble of binary-lens light curves. This is because the variety of light curve shapes and their connection to the physical parameters of the lens provide multiple opportunities for consistency checks, while also probing the distribution of binary properties among the lens population.Here, Dr. Di Stefano and collaborators will develop the necessary tools to systematically find and interpret binary lens events in the data collected by monitoring programs of the past, present, and future. By applying this work to data collected by several groups, the number of known binary-lens events will likely be doubled. Most important, these methods will be adaptable to data from all other monitoring programs, including the wide-field surveys, the Panoramic Survey Telescope & Rapid Response System (Pan-STARRS), and the Large Synoptic Survey Telescope (LSST).This work will also address the automated detection and classification of variability in images, which has broad application, to, e.g., biology. Graduate and undergraduate students will play important roles at every stage of the work. Dr. Di Stefano is also involved in an outreach program with the Cambridge public schools which will include discussions of this work with students in grades K-8.

该项目涉及解释引力微透镜事件的信号，以搜索银河系晕中的大质量致密晕天体（MACHO）。如果光环暗物质的很大一部分由 MACHO 组成，那么监测程序应该会发现比已知恒星群体产生的更多的微透镜事件。过去 15 年中已发现超过 2500 个微透镜事件。目前的发现速度约为每年 600 个，并且随着新监测计划的开始，这一速度将会很快增加。大多数光变曲线都是标准点光源、点透镜类型。这些“普通”光变曲线是高度退化的：在没有明显视差效果的情况下，只能估计透镜质量、速度和位置的组合。因此，为了确定与 MACHO 相关的贡献，我们必须依赖统计研究。尽管第一代监测程序的结果对 MACHO 分数进行了限制，但结果仍然具有高度不确定性。另一方面，二元透镜光变曲线包含更多信息。在理想情况下，可以测量透镜的位置、速度和质量，并且可以对双星的轨道间隔和质量比进行限制。因此，二元透镜可以提供强大的诊断功能。那些位于源星系的物质有可能被识别出来，并从晕中的暗质量特征中适当地减去。双元透镜光变曲线（如果存在）可以被识别，并且编码在双元透镜光变曲线中的大量信息呈现出测量单个MACHO属性的令人兴奋的前景。通过研究单个事件获得的力量对于双元透镜光变曲线的集合被放大。这是因为光变曲线形状的变化及其与晶状体物理参数的联系为一致性检查提供了多种机会，同时也探索了晶状体群体中二元特性的分布。在这里，Di Stefano 博士和合作者将开发必要的工具，以系统地查找和解释过去、现在和未来监测程序收集的数据中的二元晶状体事件。通过将这项工作应用于多个小组收集的数据，已知的双透镜事件的数量可能会增加一倍。最重要的是，这些方法将适用于来自所有其他监测项目的数据，包括广域勘测、全景勘测望远镜和快速响应系统（Pan-STARRS）以及大型综合勘测望远镜（LSST）。这项工作还将解决图像变异性的自动检测和分类问题，这在生物学等领域具有广泛的应用。研究生和本科生将在工作的每个阶段发挥重要作用。 Di Stefano 博士还参与了剑桥公立学校的一项外展计划，其中包括与 K-8 年级的学生讨论这项工作。