Implementation of disequilibrium chemistry to spectral retrieval code ARCiS and application to sixteen exoplanet transmission spectra: Indication of disequilibrium chemistry for HD 209458b and WASP-39b

Abstract

The retrieval approach is currently a standard method for deriving atmospheric properties from observed spectra of exoplanets. However, the approach ignores disequilibrium chemistry in most current retrieval codes, which can lead to misinterpretation of the metallicity or elemental abundance ratios of the atmosphere. We have implemented the disequilibrium effect of vertical mixing or quenching for the major species in hydrogen/helium-dominated atmospheres, namely $\mathrm{C}{\mathrm{H}}_4$, $\mathrm{CO}$, ${\mathrm{H}}_2\mathrm{O}$, $\mathrm{N}{\mathrm{H}}_3$, ${\mathrm{N}}_2$, and $\mathrm{C}{\mathrm{O}}_2$, for the spectral retrieval code ARCiS with a physical basis using the chemical relaxation method. Then, using ARCiS updated with this module, we have performed retrievals of the observed transmission spectra of 16 exoplanets with sizes ranging from Jupiter to mini-Neptune. As a result, we find indications of disequilibrium chemistry for HD 209458b ($\ge 4.1\sigma$) and WASP-39b ($\ge 2.7\sigma$). The retrieved spectrum of HD 209458b exhibits a strong $\mathrm{N}{\mathrm{H}}_3$ absorption feature at 10.5 $\mu$m accessible by JWST owing to an enhanced abundance of $\mathrm{N}{\mathrm{H}}_3$ due to the quenching effect. This feature is absent in the spectrum retrieved assuming equilibrium chemistry, which makes HD 209458b an ideal target for studying disequilibrium chemistry in exoplanet atmospheres. Moreover, for HAT-P-11b and GJ 436b, we obtain relatively different results than for the retrieval with the equilibrium assumption, such as a $2.9\sigma$ difference for the C/O ratio. We have also examined the retrieved eddy diffusion coefficient, but could not identify a trend over the equilibrium temperature, possibly due to the limits of the current observational precision.

arXiv comment37 pages, 7 figures, accepted for publication in Astronomy & Astrophysics

References in corpus (87)

• Array Programming with NumPy
• The James Webb Space Telescope
• Bayes in the sky: Bayesian inference and model selection in cosmology
• The effects of snowlines on C/O in planetary atmospheres
• A continuum from clear to cloudy hot-Jupiter exoplanets without primordial water depletion
• Clouds in the atmosphere of the super-Earth exoplanet GJ 1214b
• The chemical make-up of the Sun: A 2020 vision
• petitRADTRANS: a Python radiative transfer package for exoplanet characterization and retrieval
• On the radiative equilibrium of irradiated planetary atmospheres
• Disequilibrium Carbon, Oxygen, and Nitrogen Chemistry in the Atmospheres of HD 189733b and HD 209458b
• The prevalence of dust on the exoplanet HD 189733b from Hubble and Spitzer observations
• Atmospheric Retrieval for Super-Earths: Uniquely Constraining the Atmospheric Composition with Transmission Spectroscopy
• The imprint of exoplanet formation history on observable present-day spectra of hot Jupiters
• A Systematic Retrieval Analysis of Secondary Eclipse Spectra I: A Comparison of Atmospheric Retrieval Techniques
• 3D mixing in hot Jupiter atmospheres. I. application to the day/night cold trap in HD 209458b
• A featureless transmission spectrum for the Neptune-mass exoplanet GJ 436b
• Water Vapor in the Spectrum of the Extrasolar Planet HD 189733b: 1. the Transit
• HD 209458b in New Light: Evidence of Nitrogen Chemistry, Patchy Clouds and Sub-Solar Water
• Tau-REx I: A next generation retrieval code for exoplanetary atmospheres
• Photochemistry in Terrestrial Exoplanet Atmospheres I: Photochemistry Model and Benchmark Cases
• Equilibrium chemistry down to 100 K - Impact of silicates and phyllosilicates on carbon/oxygen ratio
• Thermal Emission and Albedo Spectra of Super Earths with Flat Transmission Spectra
• A chemical model for the atmosphere of hot Jupiters
• KROME - a package to embed chemistry in astrophysical simulations
• Dynamics and Disequilibrium Carbon Chemistry in Hot Jupiter Atmospheres, With Application to HD 209458b
• A Sub-Neptune Exoplanet with a Low-Metallicity Methane-Depleted Atmosphere and Mie-Scattering Clouds
• Aerosol Composition of Hot Giant Exoplanets Dominated by Silicates and Hydrocarbon Hazes
• HST hot-Jupiter transmission spectral survey: detection of potassium in WASP-31b along with a cloud deck and Rayleigh scattering
• Mass-Metallicity Trends in Transiting Exoplanets from Atmospheric Abundances of H${}_2$O, Na, and K
• Methane, Carbon Monoxide, and Ammonia in Brown Dwarfs and Self-Luminous Giant Planets
• Quantitatively Assessing the Role of Clouds in the Transmission Spectrum of GJ 1214b
• Retrieving scattering clouds and disequilibrium chemistry in the atmosphere of HR 8799e
• A Systematic Retrieval Analysis of Secondary Eclipse Spectra II: A Uniform Analysis of Eight Planets and Their C to O Ratios
• VULCAN: an Open-Source, Validated Chemical Kinetics Python Code for Exoplanetary Atmospheres
• HAT-P-26b: A Neptune-Mass Exoplanet with a Well Constrained Heavy Element Abundance
• HST hot Jupiter Transmission Spectral Survey: A detection of Na and strong optical absorption in HAT-P-1b
• HST hot Jupiter transmission spectral survey: evidence for aerosols and lack of TiO in the atmosphere of WASP-12b
• Bayesian Analysis of Hot Jupiter Radius Anomalies: Evidence for Ohmic Dissipation?
• An HST Optical to Near-IR Transmission Spectrum of the Hot Jupiter WASP-19b: Detection of Atmospheric Water and Likely Absence of TiO
• Five carbon- and nitrogen-bearing species in a hot giant planet's atmosphere
• Setting the volatile composition of (exo)planet-building material. Does chemical evolution in disk midplanes matter?
• The Atmospheric Chemistry of GJ 1214b: Photochemistry and Clouds
• Molecular abundances and C/O ratios in chemically evolving planet-forming disk midplanes
• The Complete transmission spectrum of WASP-39b with a precise water constraint
• The ExoMolOP Database: Cross-sections and k-tables for Molecules of Interest in High-Temperature Exoplanet Atmospheres
• An absolute sodium abundance for a cloud-free 'hot Saturn' exoplanet
• Pseudo 2D chemical model of hot Jupiter atmospheres: application to HD 209458b and HD 189733b
• Photochemistry in Terrestrial Exoplanet Atmospheres II: H2S and SO2 Photochemistry in Anoxic Atmospheres
• Retrieval analysis of 38 WFC3 transmission spectra and resolution of the normalisation degeneracy
• Forward and Inverse Modeling of the Emission and Transmission Spectrum of GJ 436b: Investigating Metal Enrichment, Tidal Heating, and Clouds
• Trends in Atmospheric Properties of Neptune-Size Exoplanets
• A Spitzer Transmission Spectrum for the Exoplanet GJ 436b, Evidence for Stellar Variability, and Constraints on Dayside Flux Variations
• A Chemical Kinetics Network for Lightning and Life in Planetary Atmospheres
• Impact of occultations of stellar active regions on transmission spectra: Can occultation of a plage mimic the signature of a blue sky?
• Hubble Space Telescope hot Jupiter Transmission Spectral Survey: detection of water in HAT-P-1b from Wide Field Camera 3 near-infrared spatial scan observations
• The Intrinsic Temperature and Radiative-Convective Boundary Depth in the Atmospheres of Hot Jupiters
• Source of Atomic Hydrogen in the Atmosphere of HD 209458b
• The impact of atmospheric circulation on the chemistry of the hot Jupiter HD 209458b
• Theoretical transmission spectra of exoplanet atmospheres with hydrocarbon haze: Effect of creation, growth, and settling of haze particles. I. Model description and first results
• The Deep Water Abundance on Jupiter: New Constraints from Thermochemical Kinetics and Diffusion Modeling
• Spitzer Transits of the Super-Earth GJ1214b and Implications for Its Atmosphere
• Global-mean Vertical Tracer Mixing in Planetary Atmospheres I: Theory and Fast-rotating Planets
• The ARCiS framework for Exoplanet Atmospheres: Modelling Philosophy and Retrieval
• Implications of three-dimensional chemical transport in hot Jupiter atmospheres: results from a consistently coupled chemistry-radiation-hydrodynamics model
• Vertical Tracer Mixing in Hot Jupiter Atmospheres
• Microphysics of KCl and ZnS Clouds on GJ 1214b
• Photolytic Hazes in the Atmosphere of 51 Eri b
• Three-Dimensional Circulation Driving Chemical Disequilibrium in WASP-43b
• HST hot-Jupiter transmission spectral survey: Clear skies for cool Saturn WASP-39b
• 2.5-D retrieval of atmospheric properties from exoplanet phase curves: Application to WASP-43b observations
• The ARCiS framework for Exoplanet Atmospheres: The Cloud Transport Model
• Towards a more complex description of chemical profiles in exoplanets retrievals: A 2-layer parameterisation
• Sulfur Hazes in Giant Exoplanet Atmospheres: Impacts on Reflected Light Spectra
• Super-Rayleigh Slopes in Transmission Spectra of Exoplanets Generated by Photochemical Haze
• Observable signatures of wind--driven chemistry with a fully consistent three dimensional radiative hydrodynamics model of HD 209458b
• Updated Parameters and a New Transmission Spectrum of HD 97658b
• Towards Consistent Modeling of Atmospheric Chemistry and Dynamics in Exoplanets: Validation and Generalization of Chemical Relaxation Method
• The 3D thermal, dynamical and chemical structure of the atmosphere of HD 189733b: implications of wind-driven chemistry for the emission phase curve
• An HST/STIS Optical Transmission Spectrum of Warm Neptune GJ 436b
• A Hubble PanCET Study of HAT-P-11b: A Cloudy Neptune with a Low Atmospheric Metallicity
• Revisiting Spitzer transit observations with Independent Component Analysis: new results for the GJ436 system
• Evidence for disequilibrium chemistry from vertical mixing in hot Jupiter atmospheres. A comprehensive survey of transiting close-in gas giant exoplanets with warm-Spitzer/IRAC
• 2D Retrieval Frameworks for Hot Jupiter Phase Curves
• Detection of Na, K and H${}_2$O in the hazy atmosphere of WASP-6b
• The composition of hot Jupiter atmospheres assembled within chemically evolved protoplanetary discs
• Optical to near-infrared transmission spectrum of the warm sub-Saturn HAT-P-12b
• The widest broadband transmission spectrum (0.38-1.71 $\mu$m) of HD 189733b from ground-based chromatic Rossiter-McLaughlin observations

Cited by in corpus (27)

• Early Release Science of the Exoplanet WASP-39b with JWST NIRSpec G395H
• Early Release Science of the exoplanet WASP-39b with JWST NIRCam
• Chemical Diversity in Protoplanetary Disks and Its Impact on the Formation History of Giant Planets
• JWST transmission spectroscopy of HD 209458b: a super-solar metallicity, a very low C/O, and no evidence of CH4, HCN, or C2H2
• The GAPS Programme with HARPS-N at TNG. XXXV. Fundamental properties of transiting exoplanet host stars
• Early Insights for Atmospheric Retrievals of Exoplanets using JWST Transit Spectroscopy
• 15NH3 in the atmosphere of a cool brown dwarf
• Grid of pseudo-2D chemistry models for tidally locked exoplanets -- II. The role of photochemistry
• Exoplanet atmosphere retrievals in 3D using phase curve data with ARCiS: application to WASP-43b
• Nitrogen as a Tracer of Giant Planet Formation. I.: A Universal Deep Adiabatic Profile and Semi-analytical Predictions of Disequilibrium Ammonia Abundances in Warm Exoplanetary Atmospheres
• Measuring Elemental Abundances of JWST Target Stars for Exoplanet Characterization I. FGK Stars
• Ariel stellar characterisation: I -- homogeneous stellar parameters of 187 FGK planet host stars Description and validation of the method
• Data availability and requirements relevant for the Ariel space mission and other exoplanet atmosphere applications
• Investigating the detectability of hydrocarbons in exoplanet atmospheres with JWST
• Oxygen depletion in giant planets with different formation histories
• A Mini-Chemical Scheme with Net Reactions for 3D GCMs I.: Thermochemical Kinetics
• Measuring Tracers of Planet Formation in the Atmosphere of WASP-77A b: Sub-stellar O/H and C/H ratios, with a stellar C/O ratio and a potentially Super-stellar Ti/H ratio
• Molecular tracers of planet formation in the atmospheres of hot Jupiters
• Constraining the formation of WASP-39b using JWST transit spectroscopy
• Thermal Emission from the hot Jupiter WASP-103b in J and Ks Bands
• A physically derived eddy parameterization for giant planet atmospheres with application on hot-Jupiter atmospheres
• Using a neural network approach to accelerate disequilibrium chemistry calculations in exoplanet atmospheres
• A re-analysis of equilibrium chemistry in five hot Jupiters
• Kinetic and photochemical disequilibrium in the potentially carbon-rich atmosphere of the warm-Jupiter WASP-69b
• Detection of CO${}_2$, CO, and H${}_2$O in the atmosphere of the warm sub-Saturn HAT-P-12b
• Atmospheric retrieval of Subaru/IRD high-resolution spectrum of the archetype T-type brown dwarf Gl 229 B
• A Cloudy Fit to the Atmosphere of WASP-107 b