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Arxiv: Towards atmospheric retrievals of panchromatic light-curves: ExPLOR-ing generalized inversion techniques for transiting exoplanets with JWST and Ariel Published: 3/4/2024 7:34:26 PM Updated: 3/4/2024 7:34:26 PM

Paper abstract: Conventional atmospheric retrieval codes are designed to extract information,such as chemical abundances, thermal structures and cloud properties, fromfully "reduced" spectra obtained during transit or eclipse. Reduced spectra,however, are assembled by fitting a series of simplified light-curves to timeseries observations, wavelength-by-wavelength. Thus, spectra are apost-processed summary statistics of the original data, which by definitiondoes not encode all the available information (i.e., astrophysical signal,model covariance, instrumental noise). Here, we explore an alternativeinversion strategy where the atmospheric retrieval is performed on thelight-curve directly -- i.e., closer to the data. This method is implemented inExPLOR (EXoplanet Panchromatic Light-curve Observation and Retrieval), a novelatmospheric retrieval code inheriting from the TauREx project. By explicitlyconsidering time in the model, ExPLOR naturally handles transit, eclipse,phase-curve and other complex geometries for transiting exoplanets. In thispaper, we have validated this new technique by inverting simulated panchromaticlight-curves. The model was tested on realistic simulations of a WASP-43b likeexoplanet as observed with the James Webb Space Telescope (JWST) and Arieltelescope. By comparing our panchromatic light-curve approach againstconventional spectral retrievals on mock scenarios, we have identified keybreaking points in information and noise propagation when employing pastliterature techniques. Throughout the paper, we discuss the importance ofdeveloping "closer-to-data" approaches such as the method presented in thiswork, and highlight the inevitable increase in model complexity and computingrequirements associated with the recent JWST revolution.