A retrieval challenge exercise for the Ariel mission

Experimental Astronomy, vol. 53, pp. 447–471

Abstract

Abstract The Ariel mission, due to launch in 2029, will obtain spectroscopic information for 1000 exoplanets, providing an unprecedented opportunity for comparative exoplanetology. Retrieval codes - parameteric atmospheric models coupled with an inversion algorithm - represent the tool of choice for interpreting Ariel data. Ensuring that reliable and consistent results can be produced by these tools is a critical preparatory step for the mission. Here, we present the results of a retrieval challenge. We use five different exoplanet retrieval codes to analyse the same synthetic datasets, and test a) the ability of each to recover the correct input solution and b) the consistency of the results. We find that generally there is very good agreement between the five codes, and in the majority of cases the correct solutions are recovered. This demonstrates the reproducibility of retrievals for transit spectra of exoplanets, even when codes are not previously benchmarked against each other.

Authors 8

1. J. K. Barstow corresponding

   The Open University

   Affiliation as printed

   School of Physical Sciences, The Open University, Milton Keynes, UK

   School of Physical Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK

2. Quentin Changeat

   University College London

   Affiliation as printed

   Department of Physics and Astronomy, University College London, London, UK

   Department of Physics and Astronomy, University College London, Gower Street, WC1E 6BT, London, UK

3. Katy L. Chubb Aachen

   Space Research Organisation Netherlands

   Affiliation as printed

   SRON, Utrecht, Netherlands

   SRON, Sorbonnelaan 2, 3584 CA, Utrecht, Netherlands

4. Patricio E. Cubillos

   Austrian Academy of Sciences · Space Research Institute

   Affiliation as printed

   Space Research Institute, Austrian Academy of Science, Graz, Austria

   Space Research Institute, Austrian Academy of Science, Wolfgang BaumjohannSchmiedlstrasse 6, A-8042, Graz, Austria

5. Billy Edwards

   University College London

   Affiliation as printed

   Department of Physics and Astronomy, University College London, London, UK

   Department of Physics and Astronomy, University College London, Gower Street, WC1E 6BT, London, UK

6. Ryan J. MacDonald

   Cornell University

   Affiliation as printed

   Department of Astronomy, Cornell University, Ithaca, USA

   Department of Astronomy, Cornell University, 404 Space Sciences Building, 14853, Ithaca, NY, USA

7. Michiel Min Aachen

   Space Research Organisation Netherlands

   Affiliation as printed

   SRON, Utrecht, Netherlands

   SRON, Sorbonnelaan 2, 3584 CA, Utrecht, Netherlands

8. Ingo P. Waldmann

   University College London

   Affiliation as printed

   Department of Physics and Astronomy, University College London, London, UK

   Department of Physics and Astronomy, University College London, Gower Street, WC1E 6BT, London, UK