Rocchetto, M;
Waldmann, IP;
Venot, O;
Lagage, P-O;
Tinetti, G;
(2016)
Exploring biases of atmospheric retrievals in simulated jwst transmission spectra of hot jupiters.
The Astrophysical Journal
, 833
(1)
10.3847/1538-4357/833/1/120.
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Abstract
With a scheduled launch in 2018 October, the James Webb Space Telescope (JWST) is expected to revolutionize the field of atmospheric characterization of exoplanets. The broad wavelength coverage and high sensitivity of its instruments will allow us to extract far more information from exoplanet spectra than what has been possible with current observations. In this paper, we investigate whether current retrieval methods will still be valid in the era of JWST, exploring common approximations used when retrieving transmission spectra of hot Jupiters. To assess biases, we use 1D photochemical models to simulate typical hot Jupiter cloud-free atmospheres and generate synthetic observations for a range of carbon-to-oxygen ratios. Then, we retrieve these spectra using TauREx, a Bayesian retrieval tool, using two methodologies: one assuming an isothermal atmosphere, and one assuming a parameterized temperature profile. Both methods assume constant-with-altitude abundances. We found that the isothermal approximation biases the retrieved parameters considerably, overestimating the abundances by about one order of magnitude. The retrieved abundances using the parameterized profile are usually within 1σ of the true state, and we found the retrieved uncertainties to be generally larger compared to the isothermal approximation. Interestingly, we found that by using the parameterized temperature profile we could place tight constraints on the temperature structure. This opens the possibility of characterizing the temperature profile of the terminator region of hot Jupiters. Lastly, we found that assuming a constant-with-altitude mixing ratio profile is a good approximation for most of the atmospheres under study.
| Type: | Article |
|---|---|
| Title: | Exploring biases of atmospheric retrievals in simulated jwst transmission spectra of hot jupiters |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.3847/1538-4357/833/1/120 |
| Publisher version: | http://dx.doi.org/10.3847/1538-4357/833/1/120 |
| Language: | English |
| Additional information: | This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Methods: data analysis, methods: statistical, techniques: spectroscopic, WEBB-SPACE-TELESCOPE, EXOPLANET HD 189733B, INFRARED-EMISSION-SPECTRUM, WARM-SPITZER PHOTOMETRY, GREY ANALYTICAL-MODEL, EXTRASOLAR PLANET, C/O RATIO, LINE LIST, GJ 436B, TRANSITING EXOPLANETS |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery.ucl.ac.uk/id/eprint/1524013 |
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