An Information-Theoretic Approach to Optimize JWST Observations and Retrievals of Transiting Exoplanet Atmospheres

Abstract

We provide an example of an analysis to explore the optimization of observations of transiting hot jupiters with JWST to characterize their atmospheres, based on a simple three-parameter forward model. We construct expansive forward model sets for eleven hot jupiters, ten of which are relatively well-characterized, exploring a range of parameters such as equilibrium temperature and metallicity, as well as considering host stars over a wide range in brightness. We compute posterior distributions of our model parameters for each planet with all of the available JWST spectroscopic modes and several programs of combined observations and compute their effectiveness using the metric of estimated mutual information per degree of freedom. From these simulations, clear trends emerge that provide guidelines for designing a JWST observing program. We demonstrate that these guidelines apply over a wide range of planet parameters and target brightnesses for our simple forward model.

Accepted to ApJ, 25 pages, 14 figures, 8 tables

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• Exoplanet Reflected Light Spectroscopy with PICASO
• A sub-Neptune sized planet transiting the M2.5-dwarf G 9-40: Validation with the Habitable-zone Planet Finder
• Information Content Analysis for Selection of Optimal JWST Observing Modes for Transiting Exoplanet Atmospheres
• The Metal-Rich Atmosphere of the Neptune HAT-P-26b
• An Atmospheric Retrieval of the Brown Dwarf Gliese 229B
• The PHOENIX Exoplanet Retrieval Algorithm and Using H${}^{-}$ Opacity as a Probe in Ultra-hot Jupiters
• Information content of JWST-NIRSPEC transmission spectra of warm Neptunes
• Investigating the detectability of hydrocarbons in exoplanet atmospheres with JWST