Characterization of an Instrument Model for Exoplanet Transit Spectrum Estimation through Wide Scale Analysis on HST Data

Abstract

Instrument models (IMs) enable the reduction of systematic error in transit spectroscopy light curve data, but, since the model formulation can influence the estimation of science model parameters, characterization of the instrument model effects is crucial to the interpretation of the reduced data. We analyze a simple instrument model and assess its validity and performance across Hubble WFC3 and STIS instruments. Over a large, n=63, sample of observed targets, an MCMC sampler computes the parent distribution of each instrument model parameter. Possible parent distribution functions are then fit and tested against the empirical IM distribution. Correlation and other analyses are then performed to find IM relationships. The model is shown to perform well across the 2 instruments and 3 filters analyzed and, further, the Student's t-distribution is shown to closely fit the empirical parent distribution of IM parameters and the Gaussian is shown to poorly model the observed distribution. This parent distribution can be used in the MCMC prior fitting and demonstrates IM consistency for wide scale atmospheric analysis using this model. Finally, we propose a simple metric based on light curve residuals to determine model performance, and we demonstrate its ability to determine whether a derived spectrum under this IM is high quality and robust.

arXiv comment19 pages, 14 figures, accepted for publication in Astronomical Journal

References in corpus (15)

• A continuum from clear to cloudy hot-Jupiter exoplanets without primordial water depletion
• Clouds in the atmosphere of the super-Earth exoplanet GJ 1214b
• Infrared Transmission Spectroscopy of the Exoplanets HD209458b and XO-1b Using the Wide Field Camera-3 on the Hubble Space Telescope
• PandExo: A Community Tool for Transiting Exoplanet Science with JWST & HST
• HST hot Jupiter Transmission Spectral Survey: A detection of Na and strong optical absorption in HAT-P-1b
• A new approach to analysing HST spatial scans: the transmission spectrum of HD 209458 b
• Reliable inference of exoplanet light curve parameters using deterministic and stochastic systematics models
• Marginalising instrument systematics in HST WFC3 transit lightcurves
• Detection of an Atmosphere on a Rocky Exoplanet
• An HST/STIS Optical Transmission Spectrum of Warm Neptune GJ 436b
• Robust Radio Interferometric Calibration Using the t-Distribution
• ExoTiC-ISM: A Python package for marginalised exoplanet transit parameters across a grid of systematic instrument models
• Detection of Aerosols at Microbar Pressures in an Exoplanet Atmosphere
• Bayesian Methods for Joint Exoplanet Transit Detection and Systematic Noise Characterization
• Analyzing Eight Years of Transiting Exoplanet Observations Using WFC3's Spatial Scan Monitor

Cited by in corpus (2)

• A Temperature Trend for Clouds and Hazes in Exoplanets Atmospheres
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