Observational biases for transiting planets
Observational biases for transiting planets
复制标题
凌日行星的观测偏差
DOI：
10.1093/mnras/stw1926
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发表时间：
2016
影响因子：
4.8
通讯作者：
E. Sandford
中科院分区：
文献类型：
--
作者：
D. Kipping;E. Sandford
观察偏差扭曲了我们对自然的看法，使得我们在感兴趣的调查人群中看到的模式往往不能代表我们所寻求的真相。目前，凌日行星代表了距其恒星 1 个天文单位以内的系外行星整体特性的最丰富的数据集。然而，由于几何和检测驱动的影响，传输方法本质上是有偏差的。在这项工作中，我们从第一原理得出影响最基本的凌日参数的总体观测偏差。通过假设梯形传输并使用条件概率，我们将这些项的预期分布推断为联合分布和边缘化形式。这些一般分析结果提供了一个基线，可以比较根据任务定制的注入/回收模拟预测的趋势，并提供一种纠正观察偏差的简单方法。我们的结果解释了为什么观察到的凌日行星群显示出不均匀的影响参数分布，并偏向于近赤道几何形状。我们还发现，观测到的近星体凌日行星的几何偏差会因近星体附近发生的较长持续时间而减弱。最后，我们预测相对于半径比的观测偏差是超二次的，缩放为 $(R_P/R_{\star})^{5/2}$，这是由增强的几何传输概率和适度较长的持续时间驱动的。
Observational biases distort our view of nature, such that the patterns we see within a surveyed population of interest are often unrepresentative of the truth we seek. Transiting planets currently represent the most informative data set on the ensemble properties of exoplanets within 1 AU of their star. However, the transit method is inherently biased due to both geometric and detection-driven effects. In this work, we derive the overall observational biases affecting the most basic transit parameters from first principles. By assuming a trapezoidal transit and using conditional probability, we infer the expected distribution of these terms both as a joint distribution and in a marginalized form. These general analytic results provide a baseline against which to compare trends predicted by mission-tailored injection/recovery simulations and offer a simple way to correct for observational bias. Our results explain why the observed population of transiting planets displays a non-uniform impact parameter distribution, with a bias towards near-equatorial geometries. We also find that the geometric bias towards observed planets transiting near periastron is attenuated by the longer durations which occur near apoastron. Finally, we predict that the observational bias with respect to ratio-of-radii is super-quadratic, scaling as $(R_P/R_{\star})^{5/2}$, driven by an enhanced geometric transit probability and modestly longer durations.