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Testing 2D temperature models in Bayesian retrievals of atmospheric properties from hot Jupiter phase curves

Abstract:

Spectroscopic phase curves of transiting hot Jupiters are spectral measurements at multiple orbital phases, giving a set of disc-averaged spectra that probe multiple hemispheres. By fitting model phase curves to observations, we can constrain the atmospheric properties of hot Jupiters, such as molecular abundance, aerosol distribution, and thermal structure, which offer insights into their atmospheric dynamics, chemistry, and formation. We propose a novel 2D temperature parametrization consisting of a dayside and a nightside to retrieve information from near-infrared phase curves and apply the method to phase curves of WASP-43b observed by HST/Wide Field Camera 3 and Spitzer/Infra-Red Array Camera. In our scheme, the temperature is constant on isobars on the nightside and varies with cosn(longitude/ϵ) on isobars on the dayside, where n and ϵ are free parameters. We fit all orbital phases simultaneously using the radiative transfer package NEMESISPY coupled to a Bayesian inference code. We first validate the performance of our retrieval scheme with synthetic phase curves generated from a Global Circulation Model and find that our 2D scheme can accurately retrieve the latitudinally averaged thermal structure and constrain the abundance of H2O and CH4. We then apply our 2D scheme to the observed phase curves of WASP-43b and find: (1) The dayside temperature–pressure profiles do not vary strongly with longitude and are non-inverted. (2) The retrieved nightside temperatures are extremely low, suggesting significant nightside cloud coverage. (3) The H2O volume mixing ratio is constrained to 5.6 × 10−5–4.0 × 10−4, and we retrieve an upper bound for CH4 mixing ratio at ∼10−6.

Publication status:
Published
Peer review status:
Peer reviewed

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Publisher copy:
10.1093/mnras/stad2555

Authors


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Role:
Author
ORCID:
0009-0006-2395-6197
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Institution:
University of Oxford
Division:
MPLS
Department:
Physics
Sub department:
Atmos Ocean & Planet Physics
Oxford college:
St Anne's College
Role:
Author
ORCID:
0000-0002-6772-384X
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Role:
Author
ORCID:
0000-0003-3726-5419


Publisher:
Oxford University Press
Journal:
Monthly Notices of the Royal Astronomical Society More from this journal
Volume:
525
Issue:
4
Pages:
5146-5167
Publication date:
2023-08-25
Acceptance date:
2023-08-15
DOI:
EISSN:
1365-2966
ISSN:
0035-8711


Language:
English
Keywords:
Pubs id:
1518112
Local pid:
pubs:1518112
Deposit date:
2023-10-11

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