Separating Flare and Secondary Atmospheric Signals with; RADYN; Modeling of Near-infrared JWST Transmission Spectroscopy Observations of TRAPPIST-1
Journal Article
Overview
abstract
Abstract; ; Although TRAPPIST-1’s temperate planets have the highest transmission signals of any known system, flares contaminate 50%–70% of transits at the 1000 ppm level, far above 100 ppm secondary atmospheric signals. Efforts to mitigate flare contamination and assess impacts on radiation environments are each hampered by a lack of empirical spectral analysis and physics-based modeling. We present spectrotemporal analysis and radiative-hydrodynamic modeling of 5.5 hr of NIRISS and NIRSpec observations of six TRAPPIST-1 flares of 2.2–8.7 × 10; 30; erg. The flare lines and continua are characterized using grid searches of; RADYN; beam-heating models spanning 10; 4; times in electron beam parameters. Best-fit models indicate these flares result from moderate-intensity beams with emergent electron fluxes of; F; ; e; ; = 10; 12; erg s; −1; cm; −2; and energies ≤37 keV, although all models overpredict the Paschen jump. These models predict X-ray and extreme UV (XUV), far-UV, and near-UV counterparts to the IR peak fluxes of 8.9–28.9 × 10; 27; , 4.3–13.9 × 10; 26; , and 3.4–11.4 × 10; 27; erg s; −1; , respectively. Scaling the flare rate into the XUV suggests flaring contributes 1.35; ; ; ; ; ; ; ; ; −; 0.15; ; ; +; 2.0; ; ; ; ×; ; ; quiescence yr; −1; . We bin integrations of similar flare effective temperature to construct fiducial flare spectra from 2000 to 4500 K, in order to develop separate empirical and; RADYN; -based mitigation pipelines. Both pipelines are applied to all 5.5 hr of; R; = 10 data, resulting in maximum residuals from 1 to 2.8; μ; m of 100–140 ppm and typical residuals of 54 ± 14 and 65 ± 17 ppm for the empirical and; RADYN; -based pipelines, respectively. Injection testing supports a 3; σ; detection capability for CO; 2; atmospheres with features of 150–250 ppm, with weak evidence (Bayes factor ≈ 3) still obtained at 130 ppm. Our results motivate multiwavelength observations to improve model fidelity and test high-energy predictions.;
