ThERESA: Three-Dimensional Eclipse Mapping with Application to Synthetic JWST Data

TL;DR

ThERESA is a novel method for reconstructing 3D exoplanet atmospheric structures from eclipse data by combining 2D thermal maps at different wavelengths with vertical placement, enabling efficient and accurate 3D retrievals from JWST observations.

Contribution

It introduces a new approach to retrieve 3D thermal structures by combining 2D maps at each wavelength with vertical placement, simplifying complex models for data fitting.

Findings

Successfully retrieved 3D thermal structure of a synthetic hot-Jupiter.

Recovered key atmospheric features like hotspot shift and thermal inversion.

Model with latitude-dependent depths outperforms single-pressure models.

Abstract

Spectroscopic eclipse observations, like those possible with the James Webb Space Telescope, should enable 3D mapping of exoplanet daysides. However, fully-flexible 3D planet models are overly complex for the data and computationally infeasible for data-fitting purposes. Here, we present ThERESA, a method to retrieve the 3D thermal structure of an exoplanet from eclipse observations by first retrieving 2D thermal maps at each wavelength and then placing them vertically in the atmosphere. This approach allows the 3D model to include complex thermal structures with a manageable number of parameters, hastening fit convergence and limiting overfitting. An analysis runs in a matter of days. We enforce consistency of the 3D model by comparing vertical placement of the 2D maps with their corresponding contribution functions. To test this approach, we generated a synthetic JWST NIRISS-like observation of a single hot-Jupiter eclipse using a global circulation model of WASP-76b and retrieved its 3D thermal structure. We find that a model which places the 2D maps at different depths depending on latitude and longitude is preferred over a model with a single pressure for each 2D map, indicating that ThERESA is able to retrieve 3D atmospheric structure from JWST observations. We successfully recover the temperatures of the planet's dayside, the eastward shift of its hotspot, and the thermal inversion. ThERESA is open-source and publicly available as a tool for the community.