An Empirical Bayesian Approach to Limb-darkening in Modeling WASP-121b Transit Light Curves

Abstract

We present a novel, iterative method using an empirical Bayesian approach for modeling the limb darkened WASP-121b transit from the TESS light curve. Our method is motivated by the need to improve $R_p/R_{\ast }$ estimates for exoplanet atmosphere modeling, and is particularly effective with the limb darkening (LD) quadratic law requiring no prior central value from stellar atmospheric models. With the non-linear LD law, the method has all the advantages of not needing atmospheric models but does not converge. The iterative method gives a different $R_p/R_{\ast }$ for WASP-121b at a significance level of 1$\sigma$ when compared with existing non-iterative methods. To assess the origins and implications of this difference, we generate and analyze light curves with known values of the limb darkening coefficients (LDCs). We find that non-iterative modeling with LDC priors from stellar atmospheric models results in an inconsistent $R_p/R_{\ast }$ at 1.5$\sigma$ level when the known LDC values are as those previously found when modeling real data by the iterative method. In contrast, the LDC values from the iterative modeling yields the correct value of $R_p/R_{\ast }$ to within 0.25$\sigma$. For more general cases with different known inputs, Monte Carlo simulations show that the iterative method obtains unbiased LDCs and correct $R_p/R_{\ast }$ to within a significance level of 0.3$\sigma$. Biased LDC priors can cause biased LDC posteriors and lead to bias in the $R_p/R_{\ast }$ of up to 0.82$\%$, 2.5$\sigma$ for the quadratic law and 0.32$\%$, 1.0$\sigma$ for the non-linear law. Our improvement in $R_p/R_{\ast }$ estimation is important when analyzing exoplanet atmospheres.

arXiv commentAccepted by AJ

References in corpus (50)

• emcee: The MCMC Hammer
• The Transiting Exoplanet Survey Satellite
• MultiNest: an efficient and robust Bayesian inference tool for cosmology and particle physics
• Analytic Lightcurves for Planetary Transit Searches
• A new extensive library of PHOENIX stellar atmospheres and synthetic spectra
• Multimodal nested sampling: an efficient and robust alternative to MCMC methods for astronomical data analysis
• X-ray spectral modelling of the AGN obscuring region in the CDFS: Bayesian model selection and catalogue
• Detection of an Extrasolar Planet Atmosphere
• A continuum from clear to cloudy hot-Jupiter exoplanets without primordial water depletion
• Infrared radiation from an extrasolar planet
• A Technique for Extracting Highly Precise Photometry for the Two-Wheeled Kepler Mission
• Exoplanet Atmospheres
• Exoplanetary Atmospheres: Key Insights, Challenges and Prospects
• Binning is sinning: morphological light-curve distortions due to finite integration time
• A Gaussian process framework for modelling instrumental systematics: application to transmission spectroscopy
• An ultrahot gas-giant exoplanet with a stratosphere
• Limb darkening and exoplanets: testing stellar model atmospheres and identifying biases in transit parameters
• WASP-121 b: a hot Jupiter in a polar orbit and close to tidal disruption
• An optical transmission spectrum for the ultra-hot Jupiter WASP-121b measured with the Hubble Space Telescope
• An absolute sodium abundance for a cloud-free 'hot Saturn' exoplanet
• The Stagger-grid: A grid of 3D stellar atmosphere models - IV. Limb darkening coefficients
• The effect of stellar limb darkening values on the accuracy of the planet radii derived from photometric transit observations
• Imaging the spotty surface of Betelgeuse in the H band
• Learn to Combine Modalities in Multimodal Deep Learning
• A new method to compute limb-darkening coefficients for stellar atmosphere models with spherical symmetry: the space missions TESS, Kepler, Corot, and MOST
• Deriving the stellar labels of LAMOST spectra with Stellar LAbel Machine (SLAM)
• On stellar limb darkening and exoplanetary transits
• The GTC exoplanet transit spectroscopy survey IX. Detection of Haze, Na, K, and Li in the super-Neptune WASP-127b
• Limb-darkening and exoplanets II: Choosing the Best Law for Optimal Retrieval of Transit Parameters
• HD 202772A B: A Transiting Hot Jupiter Around A Bright, Mildly Evolved Star In A Visual Binary Discovered By Tess
• High-precision stellar limb-darkening in exoplanetary transits
• Comparison of the power-2 limb-darkening law from the Stagger-grid to Kepler light curves of transiting exoplanets
• Transiting exoplanets from the CoRoT space mission. XI. CoRoT-8b: a hot and dense sub-Saturn around a K1 dwarf
• Discovery of three new transiting hot Jupiters: WASP-161 b, WASP-163 b and WASP-170 b
• The discovery of WASP-151b, WASP-153b, WASP-156b: Insights on giant planet migration and the upper boundary of the Neptunian desert
• Transiting exoplanets from the CoRoT space mission. XIII. CoRoT-13b: a dense hot Jupiter in transit around a star with solar metallicity and super-solar lithium content
• KELT-19Ab: A P~4.6 Day Hot Jupiter Transiting a Likely Am Star with a Distant Stellar Companion
• Kepler detection of a new extreme planetary system orbiting the subdwarf-B pulsator KIC10001893
• GJ 1252 b: A 1.2 $R_{\oplus }$ planet transiting an M3-dwarf at 20.4 pc
• TESS observations of the WASP-121 b phase curve
• HD219666b: A hot-Neptune from TESS Sector 1
• Ground-based detections of thermal emission from the dense hot Jupiter WASP-43b in H and Ks-bands
• Limb-darkening measurements for a cool red giant in microlensing event OGLE 2004-BLG-482
• A Repelling-Attracting Metropolis Algorithm for Multimodality
• Improving \textsl{Gaia} parallax precision with a data-driven model of stars
• Detection and characterization of an ultra-dense sub-Neptune planet orbiting the Sun-like star HD 119130
• A Catalog of Short Period Spectroscopic and Eclipsing Binaries Identified from the LAMOST & PTF Surveys
• A Multilevel Empirical Bayesian Approach to Estimating the Unknown Redshifts of 1366 BATSE Catalog Long-Duration Gamma-Ray Bursts
• Revealing stellar brightness profiles by means of microlensing fold caustics
• Fast Transit Computation Using Tabulated Stellar Intensities

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• LTD064402+245919: A Subgiant with a 1-3 M${}_{\odot }$ Undetected Companion Identified from LAMOST-TD Data
• Detecting and Monitoring Tidal Dissipation of Hot Jupiters in the Era of SiTian
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