论文标题
走向极其精确的径向速度：ii。一种用于使用多元高斯工艺来建模恒星活动的工具
Toward Extremely Precise Radial Velocities: II. A Tool For Using Multivariate Gaussian Processes to Model Stellar Activity
论文作者
论文摘要
径向速度方法是针对系外行星发现和表征的最成功的技术之一。现代光谱仪有望为理想的目标恒星〜0.2-0.5 m/s的测量精度约为0.2-0.5 m/s。但是，恒星光谱的内在变异性可以模仿和模糊这些水平的真实行星信号。 Rajpaul等。 （2015年）和琼斯等。 （2017年）提出了应用有力动机的多元高斯工艺（GP），以共同对明显的多普勒偏移和恒星活动的多个指标进行建模，以便将行星信号与各种形式的恒星变异性分开。这些方法是有希望的，但是执行必要的计算可以是计算密集的，并且在代数上乏味。在这项工作中，我们提出了一个灵活且计算高效的软件包，Gplinearodemaker.jl，用于使用单变量GPS及其衍生物的线性组合对多变量时间序列进行建模。该软件包允许用户轻松有效地应用各种多元GP模型和不同的协方差内核功能。我们通过应用Jones等人来证明gplinearodemaker.jl。 （2017）模型，以拟合来自模拟的活跃太阳光谱时间序列的表观多普勒偏移和活动指标的测量，该模型受许多不断发展的恒星斑点影响。我们展示了gplinearodemaker.jl如何使探索GP内核的不同选择的效果变得容易。我们发现，相对于广泛使用的准周期内核，局部内核可以显着提高多普勒行星搜索的灵敏度和精度。
The radial velocity method is one of the most successful techniques for the discovery and characterization of exoplanets. Modern spectrographs promise measurement precision of ~0.2-0.5 m/s for an ideal target star. However, the intrinsic variability of stellar spectra can mimic and obscure true planet signals at these levels. Rajpaul et al. (2015) and Jones et al. (2017) proposed applying a physically motivated, multivariate Gaussian process (GP) to jointly model the apparent Doppler shift and multiple indicators of stellar activity as a function of time, so as to separate the planetary signal from various forms of stellar variability. These methods are promising, but performing the necessary calculations can be computationally intensive and algebraically tedious. In this work, we present a flexible and computationally efficient software package, GPLinearOdeMaker.jl, for modeling multivariate time series using a linear combination of univariate GPs and their derivatives. The package allows users to easily and efficiently apply various multivariate GP models and different covariance kernel functions. We demonstrate GPLinearOdeMaker.jl by applying the Jones et al. (2017) model to fit measurements of the apparent Doppler shift and activity indicators derived from simulated active solar spectra time series affected by many evolving star spots. We show how GPLinearOdeMaker.jl makes it easy to explore the effect of different choices for the GP kernel. We find that local kernels could significantly increase the sensitivity and precision of Doppler planet searches relative to the widely used quasi-periodic kernel.
