Work

Precomputed aerosol extinction, scattering, and asymmetry grids for scalable atmospheric retrievals

Year: 2026

Type: article

Abstract: Context . The unprecedented wavelength coverage and sensitivity of the James Webb Space Telescope (JWST) permits us to measure the absorption features of a wide range of condensate species from silicates to Titan tholins. Atmospheric retrievals are uniquely suited for analyzing these datasets and characterizing the aerosols present in exoplanet atmospheres. However, including the optical properties of condensed particles within retrieval frameworks remains computationally expensive, which limits our ability to fully exploit JWST observations. Aims . We improve the computational efficiency and scaling behavior of aerosol models in atmospheric retrievals. This enables indepth studies that include multiple condensate species within practical timescales. Methods . Instead of computing the aerosol Mie coefficients for each sampled model, we precomputed the extinction efficiency (Q ext ), the scattering efficiency (Q scat ), and the asymmetry parameter (g) grids for seven condensate species relevant in exoplanet atmospheres (Mg 2 SiO 4 amorph sol - gel, MgSiO 3 amorph glass, MgSiO 3 amorph sol - gel, SiO 2 alpha, SiO 2 amorph, and SiO and Titan tholins). During the retrievals, the relevant values were obtained via linear interpolation between grid points. This reduced the computation times drastically. Results . The precomputed Q ext grids significantly reduce the computation time by between 1.4 and 17 times, with negligible differences on the retrieved parameters. They also scale effortlessly with the number of aerosol species while maintaining the accuracy of cloud models, thereby enabling more complex retrievals as well as broader population studies without increasing the overall error budget. The Q ext , Q scat , and g grids are freely available on Zenodo, as is a public TAUREX plugin ( TAUREX-PCQ ) that uses them. With their speed-ups, the aerosol grids presented in this paper are a significant step forward to handle both high information content and population-level datasets.

Source: Astronomy and Astrophysics

DOI: 10.1051/0004-6361/202558469

Authors: M. Voyer, Q. Changeat

Institutions: Université Paris Cité, Université Paris-Saclay, University of Groningen

Language: English

Topic: Stellar, planetary, and galactic studies

Subfield: Astronomy and Astrophysics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $1,865

Funder: Grand Équipement National De Calcul Intensif