An Open-source Bayesian Atmospheric Radiative Transfer (BART) Code. I. Design, Tests, and Application to Exoplanet HD 189733b

Joseph Harrington, Michael D. Himes, Patricio E. Cubillos, Jasmina Blecic, Patricio M. Rojo, Ryan C. Challener, Nate B. Lust, M. Oliver Bowman, Sarah D. Blumenthal, Ian Dobbs-Dixon, Andrew S.D. Foster, Austin J. Foster, M. R. Green, Thomas J. Loredo, Kathleen J. McIntyre, Madison M. Stemm, David C. Wright

Research output: Contribution to journalArticlepeer-review

Abstract

We present the open-source Bayesian Atmospheric Radiative Transfer (BART) retrieval package, which produces estimates and uncertainties for an atmosphere’s thermal profile and chemical abundances from observations. Several BART components are also stand-alone packages, including the parallel Multi-Core Markov-chain Monte Carlo (MC3), which implements several Bayesian samplers; a line-by-line radiative-transfer model, transit; a code that calculates Thermochemical Equilibrium Abundances (TEA), and a test suite for verifying radiative-transfer and retrieval codes, BARTTEST. The codes are in Python and C. BART and TEA are under a Reproducible Research (RR) license, which requires reviewed-paper authors to publish a compendium of all inputs, codes, and outputs supporting the paper’s scientific claims. BART and TEA produce the compendium’s content. Otherwise, these codes are under permissive open-source terms, as are MC3 and BARTTEST, for any purpose. This paper presents an overview of the code, BARTTEST, and an application to eclipse data for exoplanet HD 189733b. Appendices address RR methodology for accelerating science, a reporting checklist for retrieval papers, the spectral resolution required for synthetic tests, and a derivation of the effective sample size required to estimate any Bayesian posterior distribution to a given precision, which determines how many iterations to run. Paper II, by Cubillos et al., presents the underlying radiative-transfer scheme and an application to transit data for exoplanet HAT-P-11b. Paper III, by Blecic et al., discusses the initialization and post-processing routines, with an application to eclipse data for exoplanet WASP-43b. We invite the community to use and improve BART and its components at http://GitHub.com/ExOSPORTS/BART/.

Original languageEnglish (US)
Article number80
JournalPlanetary Science Journal
Volume3
Issue number4
DOIs
StatePublished - Apr 1 2022

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

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