Multidimensional Retrievals of Exoplanet Transmission Spectra

Transmission spectroscopy has proven one of the most successful methods to characterize exoplanetary atmospheres. With spectra of over 50 exoplanet atmospheres observed to date, an era of comparative exoplanetology has begun. Atmospheric retrieval techniques play a crucial role in inverting exoplanet spectra, yielding constraints on their chemical composition, temperature structure, and clouds. However, transmission spectra retrieval codes generally assume 1D atmospheric models. Recent studies have demonstrated that the 1D assumption can result in substantially biased atmospheric inferences for 3D planets with day-night or morning-evening temperature and composition gradients. With the launch of JWST, there is a critical need for multidimensional retrievals.

In this talk, I will introduce the first 3D atmospheric retrieval technique for exoplanet transmission spectra. We recently developed TRIDENT, a new rapid 3D radiative transfer code specifically optimized for 3D retrievals. I have integrated TRIDENT within the well-established POSEIDON retrieval framework, enabling 1D, 2D, and 3D retrievals of exoplanet spectra. In this talk, I will show how to retrieve multidimensional atmospheric properties from transmission spectra. Finally, I will demonstrate that many JWST Cycle 1 programs will be sensitive enough to detect multidimensional atmospheric properties.