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Arxiv: Optical Properties of Organic Haze Analogues in Water-rich Exoplanet Atmospheres Observable with JWST Published: 1/7/2023 1:14:19 AM Updated: 11/28/2023 3:51:54 PM

Paper abstract: JWST has begun its scientific mission, which includes the atmosphericcharacterization of transiting exoplanets. Some of the first exoplanets to beobserved by JWST have equilibrium temperatures below 1000 K, which is a regimewhere photochemical hazes are expected to form. The optical properties of thesehazes, which controls how they interact with light, are critical forinterpreting exoplanet observations, but relevant experimental data are notavailable. Here we measure the density and optical properties of organic hazeanalogues generated in water-rich exoplanet atmosphere experiments. We reportoptical constants (0.4 to 28.6 {\mu}m) of organic haze analogues for currentand future observational and modeling efforts covering the entire wavelengthrange of JWST instrumentation and a large part of Hubble. We use these opticalconstants to generate hazy model atmospheric spectra. The synthetic spectrashow that differences in haze optical constants have a detectable effect on thespectra, impacting our interpretation of exoplanet observations. This studyemphasizes the need to investigate the optical properties of hazes formed indifferent exoplanet atmospheres, and establishes a practical procedure todetermine such properties.