Using Atomic and Molecular Data to Model Biosignature Abundances in Exoplanetary Atmospheres

We are developing Geant4-EXOPlanets (G4-EXOP), a toolkit for modeling host-star radiation transmission through planetary atmospheric layers. G4-EXOP uses eclipse geometry, capturing light propagated through the exoplanetary atmosphere and analyzing it for biosignature abundances. G4-EXOP is based on Geant4, a Monte Carlo program package enabling modeling of radiation and particle transmission through matter. Our toolkit uses atomic and molecular data to generate emission and absorption spectra, enabling characterization of abundances from line strengths. We focus on atomic biosignatures (H, C, N, etc.) and molecules containing them (H₂O, CO₂, CH₄, etc). Phosphorus is a focus as abundances in stellar systems are vital for DNA-based life. We calculate atomic transition data using SUPERSTRUCTURE and report results for P and C. We obtain molecular data from ExoMol and report predicted oscillator strengths for H₂O and CO₂. The results include thermal Doppler Broadening. G4-EXOP will be a toolkit for modeling host-star radiation transmission through exoplanet atmospheres to characterize biosignature abundances within observations.