Observations and Analysis of Exotic Gravitational Microlensing Events

AST 0206189 Bennett该奖项支持圣母大学的大卫班尼特博士和孙洪瑞博士对“奇异”引力微透镜事件的研究。奇异事件偏离了标准的引力微透镜光变曲线，该光变曲线假设点源和单点透镜，并且源、透镜和观察者的速度恒定。这些奇异事件特别有用，因为它们比标准的微透镜光变曲线产生更多关于透镜物体的距离和质量的信息。对这些奇异的微透镜现象的研究将解决这样的问题，即银河系暗物质的很大一部分可能是由非常古老和冷却的白色矮星组成的，银河系盘中孤立的恒星质量黑洞的丰度，在千秒差距距离上测量单个恒星的质量 以及大量的低质量巨行星，它们围绕着银河系盘和凸起中的恒星运行，轨道类似于彗星。这项工作将对我们理解银河系的结构和组成、恒星和恒星残骸的基本性质以及行星形成的基本机制产生重大影响。该项目将涉及观察，数据分析和一些理论工作。观测工作将主要集中在微透镜后续观测上，这将利用OGLE-III和Super-OOO项目所预期的实时微透镜事件发现的巨大增加，这些项目刚刚开始收集数据。观测将使用南非的Boyden天文台1.5米望远镜进行，该望远镜最近已经为该观测计划进行了翻新，以及Mt。Stromlo 1.9米望远镜，位于澳大利亚，以前曾使用过。后续方案将与俄亥俄州州立大学的一个小组合作进行，该小组将为山项目作出实质性贡献。Stromlo 1.9米观测，并有近专用访问CTIO 1.5米望远镜在智利。圣母院和俄亥俄州团体的综合资源将产生24小时的微透镜事件报道。这是必要的，以便安装一个微透镜行星搜索计划，该计划将对在类海王星轨道上的行星敏感。这些观测将使行星形成的“核心吸积”模型得到严格的检验。这个微透镜后续计划还将专注于研究可以揭示孤立黑洞的微透镜视差事件。后续观测的大麦哲伦云（LMC）微透镜事件发现的主要是由超级天文台项目将产生“异国情调”的微透镜事件的功能，这将允许确定的透镜距离的一个统计上显着的事件子集。这将确定大多数LMC微透镜事件是否是由于银河系暗物质的一部分造成的，或者它们是否是由于LMC中普通恒星的透镜造成的。该奖项还将支持理论上的努力，以评估未来可能研究远距离星系或我们银河系中的类地行星中的暗物质的微透镜计划。***

AST 0206189BennettThis award supports the investigations of Dr. David Bennett and Dr. Sun Hong Rhie, at Notre Dame University, into "exotic" gravitational microlensing events. Exotic events deviate from the standard gravitational microlensing light curve which assumes a point source, and single point lens, and constant velocities for the source, lens, and observer. These exotic events are particularly useful because they yield much more information about the distance and mass of the lens object than standard microlensing light curves. The study of these exotic microlensing events will address such issues as the possibility that a substantial fraction of the Milky Way's dark matter is composed of very old and cool white dwarfs, the abundance of isolated stellar mass black holes in the Milky Way disk, mass measurements of single stars at distances of kiloparsecs from Earth, and the abundance of low-mass giant planets in Jupiter-like orbits about stars in the Galactic disk and bulge. The work will have a significant impact on our understanding of the structure and composition of our Galaxy, the fundamental properties of stars and stellar remnants, and the basic mechanism of planet formation. This project will involve observations, data analysis, and some theoretical work. The observational effort will focus primarily on microlensing follow-up observations that will take advantage of the tremendous increase in real-time microlensing event discoveries expected from the OGLE-III and Super-MACHO projects which have just begun taking data. The observations will be done with the Boyden Observatory 1.5m telescope in South Africa, which has recently been refurbished for this observing program, as well as with the Mt. Stromlo 1.9m telescope, in Australia that has been used previously. The follow-up program will be done in cooperation with an Ohio State University group which will make a substantial contribution to the Mt. Stromlo 1.9m observations, and has near dedicated access to the CTIO 1.5m telescope in Chile. The combined resources of the Notre Dame and Ohio State groups will yield 24-hour coverage of microlensing events. This is necessary in order to mount a microlensing planet search program that will be sensitive to planets down to the mass of Neptune in Jupiter-like orbits. The observations will enable a stringent test of the "core accretion" model for planet formation. This microlensing follow-up program will also focus on the study of microlensing parallax events which can reveal isolated black holes. Follow-up observations of Large Magellanic Cloud (LMC) microlensing events discovered primarily by the Super-MACHO Project will yield "exotic" microlensing event features which will allow the determination of the lens distances for a statistically significant subset of events. This will determine if most of the LMC microlensing events are due to a part of the Milky Way's dark matter, or whether they are due to lensing by ordinary stars in the LMC. This award will also support a theoretical effort to evaluate potential future microlensing programs which might study dark matter in distance galaxies or terrestrial planets in our own Galaxy. ***