Another look at the dayside spectra of WASP-43b and HD 209458b: are there scattering clouds?

TL;DR

This study reanalyzes the dayside spectra of hot Jupiters WASP-43b and HD 209458b, finding evidence for scattering clouds in some datasets of WASP-43b but not in HD 209458b, highlighting the importance of cloud scattering in atmospheric models.

Contribution

It introduces the consideration of scattering clouds in the retrieval analysis of hot Jupiter spectra, revealing their potential presence in WASP-43b's dayside atmosphere.

Findings

Scattering clouds are favored in 2 of 4 datasets for WASP-43b.

No evidence for clouds in HD 209458b's dayside spectrum.

H$_2$O abundance remains consistent across datasets and with literature.

Abstract

The search for clouds on the dayside of hot Jupiters has been disadvantaged due to hot Jupiters having a limited number of high quality space-based observations. To date, retrieval studies have found no evidence for grey clouds on the dayside, however none of these studies explored the impact of scattering clouds. In this study we reanalyse the dayside emission spectrum of the hot Jupiter WASP-43b considering the different Spitzer data in the literature. We find that, in 2 of the 4 data sets explored, retrieving with a model that contains a scattering cloud is favoured over a cloud free model by a confidence of 3.13 - 3.36 $\sigma$. The other 2 data sets finds no evidence for scattering clouds. We find that the retrieved H$_2$O abundance is consistent regardless of the Spitzer data used and is consistent with literature values. We perform the same analysis for the hot Jupiter HD 209458b and find no evidence for dayside clouds, consistent with previous studies.