TAU-REX I: A NEXT GENERATION RETRIEVAL CODE FOR EXOPLANETARY ATMOSPHERES

By Ingo P. Waldmann, Giovanna Tinetti, Marco Rocchetto, E. J. Barton, Sergei N. Yurchenko, Jonathan Tennyson. 2014

147 citations recorded by the source corpus.

Spectroscopy of exoplanetary atmospheres has become a well established method for the characterization of extrasolar planets. We here present a novel inverse retrieval code for exoplanetary atmospheres.  ?> -REx(Tau Retrieval for Exoplanets) is a line-by-line radiative transfer fully Bayesian retrieval framework.  ?> -REx includes the following features:(1) the optimized use of molecular line lists from the ExoMol project; (2) an unbiased atmospheric composition prior selection, through custom built pattern recognition software; (3) the use of two independent algorithms to fully sample the Bayesian likelihood space: nested sampling as well as a more classical Markov Chain Monte Carlo approach; (4) iterative Bayesian parameter and model selection using the full Bayesian Evidence as well as the Savage–Dickey Ratio for nested models; and (5) the ability to fully map very large parameter spaces through optimal code parallelization and scalability to cluster computing. In this publication we outline the  ?> -REx framework and demonstrate, using a theoretical hot-Jupiter transmission spectrum, the parameter retrieval and model selection. We investigate the impact of signal-to-noise ratio and spectral resolution on the retrievability of individual model parameters, both in terms of error bars on the temperature and molecular mixing ratios as well as its effect on the model’s global Bayesian evidence.

Subfields: Astronomy and Astrophysics, Atmospheric Science, Spectroscopy

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Citations in the corpus

DETECTION OF AN ATMOSPHERE AROUND THE SUPER-EARTH 55 CANCRI E (2015, methodology): “Atmospheric retrieval In order to fit the WFC3 spectrum we use T -REx (Waldmann et al. 2015b,a), a Bayesian spectral retrieval that fully maps the parameter space through the nested sampling algorithm.”
A NEW APPROACH TO ANALYZING HST SPATIAL SCANS: THE TRANSMISSION SPECTRUM OF HD 209458 b (2015, methodology): “We used the nested sampling algorithm implemented in T -REx (Waldmann et al. 2015a,b) to fully explore the parameter space and find the best fit to the WFC3 spectrum.”
The 2020 release of the ExoMol database: Molecular line lists for exoplanet and other hot atmospheres (2020, methodology): “REx [13, 14].”
A Population Study of Gaseous Exoplanets (2017, methodology): “The observed spectra were fitted using the Bayesian atmospheric retrieval framework T -REx (Waldmann et al. 2015a,b).”
NO THERMAL INVERSION AND A SOLAR WATER ABUNDANCE FOR THE HOT JUPITER HD 209458B FROM HST/WFC3 SPECTROSCOPY (2016, methodology): “…to identify which molecules are actually “detected” in this spectrum, we perform a standard nested Bayesian model comparison using the full Bayesian evidence calculation from pymultinest (Trotta 2008; Benneke & Seager 2013; Swain, Line & Deroo 2014; Waldmann et al. 2015a,b; Kreidberg et al. 2015).”
CHARACTERIZING TRANSITING EXOPLANET ATMOSPHERES WITH JWST (2015, background): “…of molecules such CO, CO2, and CH4 in addition to H2O in ∼ 10 exoplanet atmospheres (e.g., Madhusudhan & Seager 2009; Madhusudhan et al. 2011; Lee et al. 2012; Line et al. 2012; Barstow et al. 2013a,b; Benneke & Seager 2012, 2013; Line et al. 2013a, 2014a; Benneke 2015; Waldmann et al. 2015).”
HD 209458b in new light: evidence of nitrogen chemistry, patchy clouds and sub-solar water (2017, methodology): “…atmospheres in transmission (Benneke & Seager 2012, 2013; Benneke 2015; Waldmann et al. 2015a; Line & Parmentier 2016), thermal emission (Lee et al. 2012; Barstow et al. 2013; Line et al. 2013, 2016; Waldmann et al. 2015b) and reflected light (Lee et al. 2013; Lupu et al. 2016; Lavie et al. 2016).”
The nature of the TRAPPIST-1 exoplanets. (2018, background): “Radiative Article number, page 10 of 24 transfer equations are solved through the 500 layers in spherical geometry (Waldmann et al. 2015) to determine the effective transit radius of a given configuration in the Spitzer band.”
 ?> -REx. II. RETRIEVAL OF EMISSION SPECTRA (2015, methodology): “In Waldmann et al. (2015), hereafter W15, we introduce the overall architecture, data handling, minimisation/sampling routines, handling of molecular line lists, Bayesian model selection and the transmission spectroscopy forward model.”
A CONSISTENT RETRIEVAL ANALYSIS OF 10 HOT JUPITERS OBSERVED IN TRANSMISSION (2016, background): “…of transiting extrasolar planets (e.g. Lee et al. 2012; Line et al. 2013b; Stevenson et al. 2014a; Kreidberg et al. 2014, 2015; Benneke 2015; Waldmann et al. 2015), although in many cases there has been considerable degeneracy that has prevented the determination of a unique solution (e.g.…”