Dayside thermal inversion in the atmosphere of WASP-19b

Context. Observations of ultra-hot Jupiters indicate the existence of thermal inversion in their atmospheres, with dayside temperatures greater than 2200 K. Various physical mechanisms such as non-local thermal equilibrium, cloud formation, disequilibrium chemistry, ionisation, hydrodynamic waves, and associated energy have been omitted in previous spectral retrievals, while they play an important role in the thermal structure of their upper atmospheres. Aims. We aim to explore the atmospheric properties of WASP-19b to understand its largely featureless thermal spectra using a state-of-the-art atmosphere code that includes a detailed treatment of the most important physical and chemical processes at play in such atmospheres. Methods. We used the one-dimensional line-by-line radiative transfer code PHOENI