Grid-Based Atmospheric Retrievals for Reflected-Light Spectra of Exoplanets using PSGnest
arXiv:2308.00057 · doi:10.3847/1538-3881/ace43b
Abstract
Techniques to retrieve the atmospheric properties of exoplanets via direct observation of their reflected light have often been limited in scope due to computational constraints imposed by the forward-model calculations. We have developed a new set of techniques which significantly decreases the time required to perform a retrieval while maintaining accurate results. We constructed a grid of 1.4 million pre-computed geometric albedo spectra valued at discrete sets of parameter points. Spectra from this grid are used to produce models for a fast and efficient nested sampling routine called PSGnest. Beyond the upfront time to construct a spectral grid, the amount of time to complete a full retrieval using PSGnest is on the order of seconds to minutes using a personal computer. An extensive evaluation of the error induced from interpolating intermediate spectra from the grid indicates that this bias is insignificant compared to other retrieval error sources, with an average coefficient of determination between interpolated and true spectra of 0.998. We apply these new retrieval techniques to help constrain the optimal bandpass centers for retrieving various atmospheric and bulk parameters from a LuvEx-type mission observing several planetary archetypes. We show that spectral observations made using a 20\% bandpass centered at 0.73 microns can be used alongside our new techniques to make detections of and without the need to increase observing time beyond what is necessary for a signal-to-noise ratio of 10. The methods introduced here will enable robust studies of the capabilities of future observatories to characterize exoplanets.
arXiv comment32 pages, 17 figures. Accepted for publication in The Astronomical Journal
References in corpus (43)
- emcee: The MCMC Hammer
- Rank-normalization, folding, and localization: An improved for assessing convergence of MCMC
- Multimodal nested sampling: an efficient and robust alternative to MCMC methods for astronomical data analysis
- The Limiting Effects of Dust in Brown Dwarf Model Atmospheres
- A Temperature and Abundance Retrieval Method for Exoplanet Atmospheres
- SPHERE: the exoplanet imager for the Very Large Telescope
- Exoplanet Biosignatures: A Review of Remotely Detectable Signs of Life
- Atmospheric Retrieval for Super-Earths: Uniquely Constraining the Atmospheric Composition with Transmission Spectroscopy
- Planetary Spectrum Generator: an accurate online radiative transfer suite for atmospheres, comets, small bodies and exoplanets
- How to Distinguish between Cloudy Mini-Neptunes and Water/Volatile-Dominated Super-Earths
- Early Release Science of the exoplanet WASP-39b with JWST NIRSpec PRISM
- H- Opacity and Water Dissociation in the Dayside Atmosphere of the Very Hot Gas Giant WASP-18 b
- Retrieving Temperatures and Abundances of Exoplanet Atmospheres with High-Resolution Cross-Correlation Spectroscopy
- Early Release Science of the Exoplanet WASP-39b with JWST NIRSpec G395H
- Extremely Irradiated Hot Jupiters: Non-Oxide Inversions, H- Opacity, and Thermal Dissociation of Molecules
- A statistical test for Nested Sampling algorithms
- Atmospheric reconnaissance of the habitable-zone Earth-sized planets orbiting TRAPPIST-1
- A library of ATMO forward model transmission spectra for hot Jupiter exoplanets
- Characterizing Earth Analogs in Reflected Light: Atmospheric Retrieval Studies for Future Space Telescopes
- Exo-Transmit: An Open-Source Code for Calculating Transmission Spectra for Exoplanet Atmospheres of Varied Composition
- ExoGAN: Retrieving Exoplanetary Atmospheres Using Deep Convolutional Generative Adversarial Networks
- Wind of Change: retrieving exoplanet atmospheric winds from high-resolution spectroscopy
- Atmospheric Retrieval of Exoplanets
- An Ensemble of Bayesian Neural Networks for Exoplanetary Atmospheric Retrieval
- Developing Atmospheric Retrieval Methods for Direct Imaging Spectroscopy of Gas Giants in Reflected Light I: Methane Abundances and Basic Cloud Properties
- A Library of Self-Consistent Simulated Exoplanet Atmospheres
- Dreaming of atmospheres
- Interpreting High-Resolution Spectroscopy of Exoplanets Using Cross-Correlations and Supervised Machine Learning
- Neural posterior estimation for exoplanetary atmospheric retrieval
- Atmospheric Retrieval for Direct Imaging Spectroscopy of Gas Giants In Reflected Light II: Orbital Phase and Planetary Radius
- Fully scalable forward model grid of exoplanet transmission spectra
- An Approach for Retrieving Temperatures and Abundances in Brown Dwarf Atmospheres
- Accurate Machine Learning Atmospheric Retrieval via a Neural Network Surrogate Model for Radiative Transfer
- Exploring and Validating Exoplanet Atmospheric Retrievals with Solar System Analog Observations
- Reflected spectroscopy of small exoplanets II: characterization of terrestrial exoplanets
- Retrieval Analysis of the Emission Spectrum of WASP-12b: Sensitivity of Outcomes to Prior Assumptions and Implications for Formation History
- Ground-Based Transmission Spectroscopy with FORS2: A featureless optical transmission spectrum and detection of HO for the ultra-hot Jupiter WASP-103b
- Convolutional neural networks as an alternative to Bayesian retrievals
- Probing the capability of future direct imaging missions to spectrally constrain the frequency of Earth-like planets
- How do we optimally sample model grids of exoplanet spectra?
- On the Dayside Atmosphere of WASP-12b
- Detecting and Characterizing Water Vapor in the Atmospheres of Earth Analogs through Observation of the 0.94 Micron Feature in Reflected Light
- Utilizing a Database of Simulated Geometric Albedo Spectra for Photometric Characterization of Rocky Exoplanet Atmospheres