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Arxiv: Detectability of Polycyclic Aromatic Hydrocarbons in the Atmosphere of WASP-6 b with JWST NIRSpec PRISM Published: 11/12/2024 5:19:00 PM Updated: 11/12/2024 5:19:00 PM

Paper abstract: Polycyclic Aromatic Hydrocarbons (PAHs) have been detected throughout theuniverse where they play essential roles in the evolution of theirenvironments. For example, they are believed to affect atmospheric loss ratesof close-in planets and might contribute to the pre-biotic chemistry andemergence of life. Despite their importance, the study of PAHs in exoplanetatmospheres has been limited. We aim to evaluate the possibility of detectingPAHs on exoplanets considering future observations using JWST's NIRSpec PRISMmode. The hot Saturn WASP-6 b shows properties that are consistent with apotential PAH presence and is thus used as a case study for this work. Here, wecompare the likelihoods of various synthetic haze species and theircombinations with the influence of PAHs on the transmission spectrum of WASP-6b. This is possible by applying the atmospheric retrieval code petitRADTRANS toa collection of data from previous observations. Subsequently, by exploringsynthetic, single transit JWST spectra of this planet that include PAHs, weassess if these molecules can be detected in the near future. Previousobservations support the presence of cloud/haze species in the spectrum ofWASP-6 b. While this may include PAHs, the current data do not confirm theirexistence unambiguously. Our research suggests that utilizing the JWST forfuture observations could lead to a notable advancement in the study of PAHs.Employing this telescope, we find that a PAH abundance of approximately 0.1 percent of the ISM value could be robustly detectable.