A Characteristic Planetary Feature in Double-Peaked, High-Magnification Microlensing Events
A Characteristic Planetary Feature in Double-Peaked, High-Magnification Microlensing Events
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双峰、高倍率微透镜事件中的行星特征
DOI：
10.1086/592723
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
B. Gaudi
中科院分区：
文献类型：
--
作者：
C. Han;B. Gaudi
在高倍率事件中发现了相当一部分微透镜行星，其中很大一部分在高峰期表现出双峰结构。然而，非常宽或非常近的双星也可以产生双峰高倍率事件，具有与行星产生的相同的粗略性质。传统上，区分这两种解释依赖于详细的建模，这既耗时又通常无法洞察允许区分这两类模型的可观察属性。我们研究了这两类双峰高倍率事件的形态，并确定了一种简单的诊断方法，可以用来立即区分行星和双星伙伴引起的扰动，而不需要详细的建模。这种诊断是基于光曲线峰间区域形状的差异。对于双星透镜来说，它的形状是光滑和凹陷的，而对于行星透镜来说，它往往是长方形或凸起的。在行星透镜中，这种峰间形态是由于行星中心焦散的小而弱的尖端位于两个较强的尖端之间。我们将这一诊断应用于五个观察到的双峰高倍率事件，以推断其潜在的性质。我们研究的一个推论是，对双峰、高倍率事件峰间区域的良好覆盖可能对它们的独特解释很重要。
A significant fraction of microlensing planets have been discovered in high-magnification events, and a significant fraction of these events exhibit a double-peak structure at their peak. However, very wide or very close binaries can also produce double-peaked high-magnification events, with the same gross properties as those produced by planets. Traditionally, distinguishing between these two interpretations has relied on detailed modeling, which is both time-consuming and generally does not provide insight into the observable properties that allow discrimination between these two classes of models. We study the morphologies of these two classes of double-peaked, high-magnification events and identify a simple diagnostic that can be used to immediately distinguish between perturbations caused by planetary and binary companions, without detailed modeling. This diagnostic is based on the difference in the shape of the interpeak region of the light curves. The shape is smooth and concave for binary lensing, while it tends to be either boxy or convex for planetary lensing. In planetary lensing this interpeak morphology is due to the small, weak cusp of the planetary central caustic located between the two stronger cusps. We apply this diagnostic to five observed double-peaked, high-magnification events to infer their underlying nature. A corollary of our study is that good coverage of the interpeak region of double-peaked, high-magnification events is likely to be important for their unique interpretation.