Tidal heating on Io due to its finite eccentricity was predicted to drive surface volcanic activity, which was subsequently confirmed by the Voyager spacecraft. Throughout the paper, we discuss the importance of developing “closer-to-data” approaches such as the method presented in this work, and highlight the inevitable increase in model complexity and computing requirements associated with the recent JWST revolution. By comparing our panchromatic light-curve approach against conventional spectral retrievals on mock scenarios, we have identified key breaking points in information and noise propagation when employing past literature techniques. The model was tested on realistic simulations of a WASP-43 b-like exoplanet as observed with the James Webb Space Telescope (JWST) and Ariel telescope.

In this paper, we have validated this new technique by inverting simulated panchromatic light curves. By explicitly considering time in the model, E x PLOR naturally handles transits, eclipses, phase curves, and other complex geometries for transiting exoplanets.

This method is implemented in EXoplanet Panchromatic Light curve Observation and Retrieval (E x PLOR), a novel atmospheric retrieval code inheriting from the T au RE x project. Here, we explore an alternative inversion strategy where the atmospheric retrieval is performed on the light curve directly, i.e., closer to the data. Thus, spectra are postprocessed summary statistics of the original data, which by definition do not encode all the available information (i.e., astrophysical signal, model covariance, and instrumental noise). Reduced spectra, however, are assembled by fitting a series of simplified light curves to time-series observations, wavelength by wavelength.

Conventional atmospheric retrieval codes are designed to extract information, such as chemical abundances, thermal structures, and cloud properties, from fully “reduced” spectra obtained during transit or eclipse.

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