A Short, Nonplanetary, Microlensing Anomaly: Observations and Light-Curve Analysis of MACHO 99-BLG-47
A Short, Nonplanetary, Microlensing Anomaly: Observations and Light-Curve Analysis of MACHO 99-BLG-47
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短暂的非行星微透镜异常：MACHO 99-BLG-47 的观测和光曲线分析
DOI：
10.1086/340310
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
A. Williams
中科院分区：
文献类型：
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作者：
M. Albrow;J. An;J. Beaulieu;J. Caldwell;D. Depoy;M. Dominik;B. Gaudi;A. Gould;J. Greenhill;K. Hill;S. Kane;R. Martin;J. Menzies;R. Pogge;K. Pollard;P. Sackett;K. Sahu;P. Vermaak;R. Watson;A. Williams
我们分析了PLANET和CAMO对CAMO 99-BLG-47的观测，这是第一个几乎正常的微透镜事件，高信噪比数据显示了一个覆盖良好的短持续时间异常。这种异常发生在事件的高峰附近。在正常事件的峰值附近出现的短持续时间异常，预计既来自极端分离（非常近或非常宽），也来自质量大致相等的双星透镜和行星系统。我们表明，透镜的O 99-BLG-47实际上是一个极端分离的二进制，而不是一个行星系统，从而证明了第一次，这两个重要的类事件可以区分在实践中。然而，我们发现宽二元和近二元透镜解同样很好地拟合数据，即使在Δχ2 = 1时也无法区分。这种简并在质量上比对CNO 98-SMC-1所确定的简并严重得多，因为目前的简并在放大场中跨越两个维度而不是一个维度，并且不需要显著不同的混合分数。在附录中，我们探讨了这个结果，并表明它与透镜方程的对称性有关。
We analyze PLANET and MACHO observations of MACHO 99-BLG-47, the first nearly normal microlensing event for which high signal-to-noise ratio data reveal a well-covered, short-duration anomaly. This anomaly occurs near the peak of the event. Short-duration anomalies near the peak of otherwise normal events are expected to arise both from extreme-separation (either very close or very wide), roughly equal-mass binary lenses and from planetary systems. We show that the lens of MACHO 99-BLG-47 is in fact an extreme-separation binary, not a planetary system, thus demonstrating for the first time that these two important classes of events can be distinguished in practice. However, we find that the wide-binary and close-binary lens solutions fit the data equally well and cannot be distinguished even at Δχ2 = 1. This degeneracy is qualitatively much more severe than the one identified for MACHO 98-SMC-1 because the present degeneracy spans two rather than one dimension in the magnification field and does not require significantly different blending fractions. In the Appendix, we explore this result and show that it is related to the symmetry in the lens equation.