Retrieving Temperatures and Abundances of Exoplanet Atmospheres with High-resolution Cross-correlation Spectroscopy
Retrieving Temperatures and Abundances of Exoplanet Atmospheres with High-resolution Cross-correlation Spectroscopy
复制标题
用高分辨率互相关光谱检索系外行星大气的温度和丰度
DOI：
10.3847/1538-3881/aaffd3
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
M. Line
中科院分区：
文献类型：
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作者：
M. Brogi;M. Line
高分辨率光谱学（R ≥ 25，000）最近成为探测系外行星大气中原子和分子物种的主要方法之一。然而，到目前为止，它一直缺乏一个强大的方法来提取定量约束的温度结构和分子/原子丰度。在这项工作中，我们提出了一种新的贝叶斯大气检索框架适用于高分辨率互相关光谱（HRCCS），依赖于数据和模型之间的互相关来提取行星光谱信号。我们成功地测试了模拟数据的框架，并表明它可以正确地确定大气温度和丰度的贝叶斯可信区间，允许定量探索固有的退化。此外，我们的新框架使我们能够平凡地联合收割机，并探索HRCCS和低分辨率光谱之间的协同作用，以最大限度地利用每个内包含的信息。这个框架也使我们能够定量评估的影响，分子线不透明度在高分辨率。我们适用于VLT CRIRES K-波段光谱的HD 209458 B和HD 189733 B和检索丰富的一氧化碳，但太阳下的水，这在很大程度上是不变的不同模型假设的框架。这证实了先前对这些数据集的分析，但可能与在不同波长和光谱分辨率下检测到的H2O不一致。这里提出的框架是实现空间观测站和地面高分辨率观测之间真正协同作用的第一步。
High-resolution spectroscopy (R ≥ 25,000) has recently emerged as one of the leading methods for detecting atomic and molecular species in the atmospheres of exoplanets. However, it has so far been lacking a robust method for extracting quantitative constraints on the temperature structure and molecular/atomic abundances. In this work, we present a novel Bayesian atmospheric retrieval framework applicable to high-resolution cross-correlation spectroscopy (HRCCS) that relies on the cross-correlation between data and models to extract the planetary spectral signal. We successfully test the framework on simulated data and show that it can correctly determine Bayesian credibility intervals on atmospheric temperatures and abundances, allowing for a quantitative exploration of the inherent degeneracies. Furthermore, our new framework permits us to trivially combine and explore the synergies between HRCCS and low-resolution spectroscopy to maximally leverage the information contained within each. This framework also allows us to quantitatively assess the impact of molecular line opacities at high resolution. We apply the framework to VLT CRIRES K-band spectra of HD 209458 b and HD 189733 b and retrieve abundant carbon monoxide but subsolar abundances for water, which are largely invariant under different model assumptions. This confirms previous analysis of these data sets, but is possibly at odds with detections of H2O at different wavelengths and spectral resolutions. The framework presented here is the first step toward a true synergy between space observatories and ground-based high-resolution observations.