Information Content Analysis for Selection of Optimal JWST Observing Modes for Transiting Exoplanet Atmospheres
Information Content Analysis for Selection of Optimal JWST Observing Modes for Transiting Exoplanet Atmospheres
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DOI：
10.3847/1538-3881/aa5faa
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发表时间：
2017-04-01
影响因子：
5.3
通讯作者：
Line, M. R.
中科院分区：
文献类型：
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作者：
Batalha, Natasha E.;Line, M. R.
詹姆斯·韦伯太空望远镜 (JWST) 即将于 2018 年发射，预计将彻底改变我们对系外行星大气层的认识。为了具体确定哪些观测模式对于表征各种系外行星大气最有用，我们使用了太阳系大气研究中常用的基于信息内容（IC）的方法。我们开发了一个基于这些 IC 方法的系统，用于追踪仪器和大气模型相空间，以确定哪种观测模式最适合特定类别的行星，重点关注透射光谱。具体来说，我们覆盖的大气参数空间是T - 600-1800 K，C/O - 0.55-1，[M/H] - 1-100。 x。太阳系 R - 1.39 R-J、M - 0.59 M-J 行星绕着类似 WASP-62 的恒星运行。我们还探讨了简化的不透明灰云对 IC 的影响。我们发现，在相同的观测时间下，在多种模式下获得更宽的波长覆盖范围优于在单一模式下获得更高的精度。无论行星温度和成分如何，限制终止子温度、C/O 比和金属丰度的最佳模式是 NIRISS SOSS+NIRSpec G395。如果目标的主星足够暗，可以使用 NIRSpec 棱镜，则可以使用它来代替 NIRISS SOSS+NIRSpec G395。最后，应仔细分析使用两种以上模式的观测结果，因为有时添加第三种模式会导致无法获得信息。在这些情况下，原始两种模式中较高的精度是有利的。
The James Webb Space Telescope (JWST) is nearing its launch date of 2018, and is expected to revolutionize our knowledge of exoplanet atmospheres. In order to specifically identify which observing modes will be most useful for characterizing a diverse range of exoplanetary atmospheres, we use an information content (IC) based approach commonly used in the studies of solar system atmospheres. We develop a system based upon these IC methods to trace the instrumental and atmospheric model phase space in order to identify which observing modes are best suited for particular classes of planets, focusing on transmission spectra. Specifically, the atmospheric parameter space we cover is T - 600-1800 K, C/O - 0.55-1, [M/H] - 1-100. x. Solar for an R - 1.39 R-J, M - 0.59 M-J planet orbiting a WASP-62-like star. We also explore the influence of a simplified opaque gray cloud on the IC. We find that obtaining broader wavelength coverage over multiple modes is preferred over higher precision in a single mode given the same amount of observing time. Regardless of the planet temperature and composition, the best modes for constraining terminator temperatures, C/O ratios, and metallicity are NIRISS SOSS+NIRSpec G395. If the target's host star is dim enough such that the NIRSpec prism is applicable, then it can be used instead of NIRISS SOSS+NIRSpec G395. Lastly, observations that use more than two modes should be carefully analyzed because sometimes the addition of a third mode results in no gain of information. In these cases, higher precision in the original two modes is favorable.