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arXiv 1302.6607astro-ph.EP
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系外行星食观测马尔可夫链蒙特卡罗拟合的基准检验

Benchmark Tests for Markov Chain Monte Carlo Fitting of Exoplanet Eclipse Observations

Justin C. Rogers, Mercedes Lopez-Morales, Daniel Apai, Elisabeth Adams

摘要:

对系外行星食的地面观测为行星的大气物理学提供了重要线索,但光变曲线分析中的系统学还没有完全理解。目前尚不清楚,如果测量表明近红外通量密度比模型预测的更亮,是真实的,还是分析过程的伪影。我们使用合成和真实噪声创建了一个大型模型光变曲线套件,并使用马尔可夫链蒙特卡罗(MCMC)算法测试了光变曲线建模和参数优化的常见过程。与合成白噪声模型,我们发现,输入日食信号一般恢复在10%的精度范围内的日食深度大于噪声幅度,和更高的采样率和更长的基线更小的深度。红噪声模型在输入和测量的日食信号之间看到了更大的差异,通常偏向一个方向。最后,我们发现,在真实数据中,即使使用复杂的模型来解释趋势,系统偏差也会导致显著的假食信号可能出现在非高斯分布中。为了量化偏差并验证日食测量,我们将行星宿主恒星及其几个邻居与单独选择的场星控制样本进行比较。重新检查Rogers等人(2009年)对CoRoT-1b的KS波段测量发现,$3190^{+370}_{-440}$深ppm,中心位于$ϕ_{me}$ = $0.50418^{+0.00197}_{-0.00203}$。最后,我们提供并推荐使用我们生成的选定数据集作为Eclipse建模和分析例程的基准测试,并提出验证Eclipse检测的标准。

英文摘要:

Ground-based observations of exoplanet eclipses provide important clues to the planets' atmospheric physics, yet systematics in light curve analyses are not fully understood. It is unknown if measurements suggesting near-infrared flux densities brighter than models predict are real, or artifacts of the analysis processes. We created a large suite of model light curves, using both synthetic and real noise, and tested the common process of light curve modeling and parameter optimization with a Markov Chain Monte Carlo (MCMC) algorithm. With synthetic white-noise models, we find that input eclipse signals are generally recovered within 10% accuracy for eclipse depths greater than the noise amplitude, and to smaller depths for higher sampling rates and longer baselines. Red-noise models see greater discrepancies between input and measured eclipse signals, often biased in one direction. Finally, we find that in real data, systematic biases result even with a complex model to account for trends, and significant false eclipse signals may appear in a non-Gaussian distribution. To quantify the bias and validate an eclipse measurement, we compare both the planet-hosting star and several of its neighbors to a separately-chosen control sample of field stars. Re-examining the Rogers et al. (2009) Ks-band measurement of CoRoT-1b finds an eclipse $3190^{+370}_{-440}$ ppm deep centered at $ϕ_{me}$=$0.50418^{+0.00197}_{-0.00203}$. Finally, we provide and recommend the use of selected datasets we generated as a benchmark test for eclipse modeling and analysis routines, and propose criteria to verify eclipse detections.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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