Retrieved Atmospheres and Inferred Surface Properties for Terrestrial Exoplanets Using Transmission and Reflected-light Spectroscopy

IF 3.8 Q2 ASTRONOMY & ASTROPHYSICS
Samantha Gilbert-Janizek, Victoria S. Meadows and Jacob Lustig-Yaeger
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引用次数: 0

Abstract

Future astrophysics missions will seek extraterrestrial life via transmission and direct-imaging observations. To assess habitability and biosignatures, we need robust retrieval tools to analyze observed spectra, and infer surface and atmospheric properties with their uncertainties. We use a novel retrieval tool to assess accuracy in characterizing near-surface habitability and biosignatures via simulated transmission and direct-imaging spectra, based on the Origins Space Telescope (Origins) and LUVOIR mission concepts. We assess our ability to discriminate between an Earth-like and a false-positive O3 TRAPPIST-1 e with transmission spectroscopy. In reflected light, we assess the robustness of retrieval results to unmodeled cloud extinction. We find that assessing habitability using transmission spectra may be challenging due to relative insensitivity to surface temperature and near-surface H2O abundances. Nonetheless, our order-of-magnitude H2O constraints can discriminate extremely desiccated worlds. Direct imaging is insensitive to surface temperature and subject to the radius/albedo degeneracy, but this method proves highly sensitive to surface water abundance, achieving retrieval precision within 0.1% even with partial clouds. Concerning biosignatures, Origins-like transmission observations (t = 40 hr) may detect the CO2/CH4 pair on M-dwarf planets and differentiate between biological and false-positive O3 using H2O and abundant CO. In contrast, direct-imaging observations with LUVOIR-A (t = 10 hr) are better suited to constraining O2 and O3, and may be sensitive to wavelength-dependent water cloud features, but will struggle to detect modern-Earth-like abundances of methane. For direct imaging, we weakly detect a stratospheric ozone bulge by fitting the near-UV wings of the Hartley band.
利用透射和反射光分光镜检索类地系外行星的大气层和推断表面性质
未来的天体物理学任务将通过传输和直接成像观测来寻找地外生命。为了评估宜居性和生物特征,我们需要强大的检索工具来分析观测到的光谱,并推断表面和大气属性及其不确定性。我们根据起源太空望远镜(Origins)和 LUVOIR 任务概念,使用一种新颖的检索工具来评估通过模拟透射和直接成像光谱来描述近表面宜居性和生物特征的准确性。我们评估了利用透射光谱辨别类地和假阳性 O3 TRAPPIST-1 e 的能力。在反射光下,我们评估了检索结果对未建模云消光的稳健性。我们发现,由于对表面温度和近表面 H2O 丰度相对不敏感,利用透射光谱评估宜居性可能具有挑战性。尽管如此,我们的数量级 H2O 约束条件还是可以分辨出极度干燥的世界。直接成像法对表面温度不敏感,而且受半径/反照率退化的影响,但这种方法被证明对表面水丰度高度敏感,即使在有部分云层的情况下,检索精度也能达到0.1%以内。关于生物特征,类似起源的透射观测(t = 40 小时)可以探测到 M-矮行星上的 CO2/CH4 对,并利用 H2O 和丰富的 CO 区分生物 O3 和假阳性 O3。相比之下,利用 LUVOIR-A 进行的直接成像观测(t = 10 小时)更适于对 O2 和 O3 进行约束,并可能对波长相关的水云特征很敏感,但很难探测到类似现代地球的甲烷丰度。在直接成像方面,我们通过拟合哈特利波段的近紫外翼,微弱地探测到了平流层臭氧隆起。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
The Planetary Science Journal
The Planetary Science Journal Earth and Planetary Sciences-Geophysics
CiteScore
5.20
自引率
0.00%
发文量
249
审稿时长
15 weeks
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