Thermal emission of WASP-48b in the Ks-band

TL;DR

This study detects and analyzes the thermal emission of hot Jupiter WASP-48b across multiple infrared bands, revising system parameters and comparing atmospheric models to observed data.

Contribution

First detection of WASP-48b's thermal emission in Ks-band and comprehensive multi-band analysis including system parameter revision and atmospheric modeling.

Findings

Thermal emission detected in Ks-band with contrast ratio 0.136%.

System parameters revised based on combined lightcurve data.

Both atmospheric models with and without thermal inversion fit the data.

Abstract

We report a detection of thermal emission from the hot Jupiter WASP-48b in the $K_{\rm s}$-band. We used the Wide-field Infra-red Camera on the 3.6-m Canada-France Hawaii Telescope to observe an occultation of the planet by its host star. From the resulting occultation lightcurve we find a planet-to-star contrast ratio in the Ks-band of $0.136 \pm 0.014\,\%$ , in agreement with the value of $0.109 \pm 0.027\,\%$ previously determined. We fit the two Ks-band occultation lightcurves simultaneously with occultation lightcurves in the $H$-band and the Spitzer 3.6-{\mu}m and 4.5-{\mu}m bandpasses, radial velocity data, and transit lightcurves. From this, we revise the system parameters and construct the spectral energy distribution (SED) of the dayside atmosphere. By comparing the SED with atmospheric models, we find that both models with and without a thermal inversion are consistent with the data. We find the planet's orbit to be consistent with circular ($e < 0.072$ at 3$\sigma$).