The Macho Project: 45 Candidate Microlensing Events from the First Year Galactic Bulge Data
The Macho Project: 45 Candidate Microlensing Events from the First Year Galactic Bulge Data
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Macho 项目：来自银河系核球第一年数据的 45 个候选微透镜事件
DOI：
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发表时间：
1995
期刊：
影响因子：
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通讯作者：
W. Sutherland
中科院分区：
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作者：
C. Alcock;C. Alcock;R. Allsman;D. Alves;T. Axelrod;T. Axelrod;D. Bennett;D. Bennett;K. Cook;K. Cook;Kenneth C. Freeman;K. Griest;K. Griest;J. Guern;J. Guern;M. Lehner;M. Lehner;S. Marshall;S. Marshall;H. Park;Saul Perlmutter;B. Peterson;M. Pratt;M. Pratt;P. Quinn;A. Rodgers;C. Stubbs;C. Stubbs;C. Stubbs;W. Sutherland
我们报告了在银河核球区域检测到的 45 个候选微透镜事件。这些数据来自对 1993 年观测了 190 天、包含 1260 万颗恒星的 24 个视场的分析。其中许多事件具有极高的信噪比，是引力微透镜效应的显着例子。峰值放大倍数的分布与这些事件的微透镜解释一致。使用距离和探测效率众所周知的 130 万颗“丛巨”恒星的子样本，我们发现了 13 个事件，并估计了银河核球的微透镜光学深度为 τbulge=3.9+ 1.8−1.2×10−6，在以银河坐标 l = 2.°55 和 b = 3.°64 为中心的约 12 deg2 区域内平均。这与 OGLE 合作报告的值相似，并且略高于当前的 τbulge 理论模型。光学深度也随着 | 的减小而显着增加。 b|。这些结果表明，获得大量朝向银河核球的微透镜事件是可行的，并且对此类事件的研究将对银河系及其暗晕的结构产生重要影响。
We report the detection of 45 candidate microlensing events in fields toward the Galactic bulge. These come from the analysis of 24 fields containing 12.6 million stars observed for 190 days in 1993. Many of these events are of extremely high signal-to-noise ratio and are remarkable examples of gravitational microlensing. The distribution of peak magnifications is shown to be consistent with the microlensing interpretation of these events. Using a subsample of 1.3 million “clump giant” stars whose distance and detection efficiency are well known, we find 13 events and estimate the microlensing optical depth toward the Galactic bulge as τbulge=3.9+ 1.8−1.2×10−6 averaged over an area of ~12 deg2 centered at Galactic coordinates l = 2.°55 and b = 3.°64. This is similar to the value reported by the OGLE collaboration and is marginally higher than current theoretical models for τbulge. The optical depth is also seen to increase significantly for decreasing | b |. These results demonstrate that obtaining large numbers of microlensing events toward the Galactic bulge is feasible, and that the study of such events will have important consequences for the structure of the Galaxy and its dark halo.