Atmospheric Retrieval of Brown Dwarfs

Brown dwarfs, with masses between planetary and stellar masses, offer unique insight into formation mechanisms in this transitional domain. In addition, they provide remarkable laboratories for understanding atmospheric physics in the low-irradiation regime. Recently, atmospheric retrieval techniques have been applied to brown dwarfs allowing detailed constraints on their compositions and P-T profiles. Most of the spectra used to date are from ground-based observations. In this work we use high-precision, space-based infrared spectra of a sizeable sample of brown dwarfs to obtain constraints on their chemistry and structure. We report abundance constraints on H2O, CH4, NH3, Na and K as well as C/O ratios and P-T profiles. We also present key advances in atmospheric retrieval parametrisation and optimisation methods for handling high signal-to-noise data. We discuss future applications of these methods to JWST-quality data. Finally, we consider the implications of our current retrieval estimates for formation mechanisms of brown dwarfs.

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