文章基本信息

标题：ExoReL${}^{{\mathfrak{R}}}$: A Bayesian Inverse Retrieval Framework for Exoplanetary Reflected Light Spectra
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作者：Mario Damiano ; Renyu Hu
期刊名称：The Astronomical journal
印刷版ISSN：0004-6256
电子版ISSN：1538-3881
出版年度：2020
卷号：159
期号：4
页码：2451-2467
DOI：10.3847/1538-3881/ab79a5
语种：English
出版社：American Institute of Physics
摘要：The high-contrast imaging technique is meant to provide insight into those planets orbiting several astronomical units from their host star.Space missions such as Wide-Field InfraRed Survey Telescope, Habitable Exoplanet Imaging Mission, and Large Ultra-Violet/Optical/InfraRed Surveyor will measure reflected light spectra of cold gaseous and rocky planets.To interpret these observations, we introduce ExoReL${}^{{\mathfrak{R}}}$ (Exoplanetary Reflected Light Retrieval), a novel Bayesian retrieval framework to retrieve cloud properties and atmospheric structures from exoplanetary reflected light spectra.As a unique feature, it assumes a vertically nonuniform volume mixing ratio (VMR) profile of water and ammonia, and uses it to construct cloud densities.In this way, clouds and molecular mixture ratios are consistent.We apply ExoReL${}^{{\mathfrak{R}}}$ on three test cases: two exoplanets (υ And e and 47 Uma b) and Jupiter.We show that we are able to retrieve the concentration of methane in the atmosphere, and estimate the position of clouds when the signal-to-noise ratio of the spectrum is higher than 15, in line with previous works.Moreover, we described the ability of our model to give a chemical identity to clouds, and we discussed whether or not we can observe this difference in the planetary reflection spectrum.Finally, we demonstrate how it could be possible to retrieve molecular concentrations (water and ammonia in this work) below the clouds by linking the nonuniform VMR profile to the cloud presence.This will help to constrain the concentration of water and ammonia unseen in direct measurements.
关键词：Planetary science;Planetary atmospheres;Bayesian statistics;Exoplanets;Extrasolar gas giants;Radiative transfer;Spectroscopy