Alfnoor: A Retrieval Simulation of the Ariel Target List

Abstract

In this work, we present Alfnoor, a dedicated tool optimised for population studies of exoplanet atmospheres. Alfnoor combines the latest version of the retrieval algorithm TauREx 3, with the instrument noise simulator ArielRad and enables the simultaneous retrieval analysis of a large sample of exo-atmospheres. We applied this tool to the Ariel list of planetary candidates and focus on hydrogen dominated, cloudy atmospheres observed in transit with the Tier-2 mode (medium Ariel resolution). As a first experiment, we randomised the abundances - ranging from 10${}^{-7}$ to 10${}^{-2}$ - of the trace gases, which include H${}_2$O, CH${}_4$, CO, CO${}_2$ and NH${}_3$. This exercise allowed to estimate the detection limits for Ariel Tier-2 and Tier-3 modes when clouds are present. In a second experiment, we imposed an arbitrary trend between a chemical species and the effective temperature of the planet. A last experiment was run requiring molecular abundances being dictated by equilibrium chemistry at a certain temperature. Our results demonstrate the ability of Ariel Tier-2 and Tier-3 surveys to reveal trends between the chemistry and associated planetary parameters. Future work will focus on eclipse data, on atmospheres heavier than hydrogen and will be applied also to other observatories.

33 pages, 24 figures, Accepted in AJ

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Cited by in corpus (28)

• Tracing the formation history of giant planets in protoplanetary disks with Carbon, Oxygen, Nitrogen and Sulphur
• TauREx III: A fast, dynamic and extendable framework for retrievals
• Five key exoplanet questions answered via the analysis of 25 hot Jupiter atmospheres in eclipse
• Assessing the C/O Ratio Formation Diagnostic: A Potential Trend with Companion Mass
• A comparison of chemical models of exoplanet atmospheres enabled by TauREx 3.1
• The Ariel Target List: The Impact of TESS and the Potential for Characterising Multiple Planets Within a System
• The composition of hot Jupiter atmospheres assembled within chemically evolved protoplanetary discs
• KELT-11 b: Abundances of water and constraints on carbon-bearing molecules from the Hubble transmission spectrum
• An exploration of model degeneracies with a unified phase curve retrieval analysis: The light and dark sides of WASP-43 b
• A Catalogue of Exoplanet Atmospheric Retrieval Codes
• WASP-117 b: an eccentric hot-Saturn as a future complex chemistry laboratory
• A retrieval challenge exercise for the Ariel mission
• The homogeneous characterisation of Ariel host stars
• Alfnoor: assessing the information content of Ariel's low resolution spectra with planetary population studies
• Hierarchical Bayesian Atmospheric Retrieval Modeling for Population Studies of Exoplanet Atmospheres: A Case Study on the Habitable Zone
• The Molecular Composition of Shadowed Protosolar Disk Midplanes beyond the Water Snowline
• Terminus: A Versatile Simulator for Space-based Telescopes
• Detectability of Rocky-Vapour Atmospheres on Super-Earths with Ariel
• Comparing transit spectroscopy pipelines at the catalogue level: evidence for systematic differences
• ARES VI: Viability of one-dimensional retrieval models for transmission spectroscopy characterization of exo-atmospheres in the era of JWST and Ariel
• Detecting molecules in Ariel low resolution transmission spectra
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• ExoSim 2: the new Exoplanet Observation Simulator applied to the Ariel space mission
• Disentangling Atmospheric Compositions of K2-18 b with Next Generation Facilities
• Exploring Synergies between Twinkle and Ariel: a Pilot Study