Direct imaging of cold exoplanets. A theory framework for atmospheric characterization

Upcoming space missions such as WFIRST and under-development concepts like LUVOIR or HabEx will measure the starlight reflected from cold and temperate exoplanets by direct imaging. Reflected starlight is sensitive to atmospheric depths that cannot be probed in transit (e.g. [1]) and provides a means for investigating non-transiting exoplanets. Directly imaged exoplanets observed in reflected starlight represents the next frontier in exoplanet atmospheres characterization. Thus, the theory for planning and interpreting future observations and the physics behind them is now in development [2]. The goal of this work is to understand what information can be extracted from direct imaging observations of exoplanets in reflected starlight and how robust these conclusions are. We computed synthetic spectra for more than 3 million atmospheric configurations that probe a variety of physical properties of the atmosphere. With that, we studied how degeneracies between parameters affect the atmospheric retrieval in direct imaging observations