A Comparative Simulation Study of Hot and Ultrahot Jupiter Atmospheres Using Different Ground-based High-resolution Spectrographs with Cross-correlation Spectroscopy

Abstract In the era of state-of-the-art space-borne telescopes, high-resolution ground-based observation has emerged as a crucial method for characterizing exoplanets, providing essential insights into their atmospheric compositions. In the optical and near-infrared regions, high-resolution spectroscopy has been powerful for hot Jupiters (HJs) and ultrahot Jupiters (UHJs) during their primary transits, as it can probe molecules with better sensitivity. Here, we focus on a comparative simulation study of WASP-76 b (UHJ) and WASP-77 A b (HJ) for different numbers of transits, utilizing three ground-based spectrographs, GIANO-B (Telescopio Nazionale Galileo), CARMENES (Centro Astronomico Hispano Alemán), and ANDES (European Extremely Large Telescope or E-ELT), with varying instrumental parameters, spectral coverages, and resolutions. We aim to evaluate the feasibility of using the upcoming ground-based E-ELT to probe molecules from planet atmospheres and to show how it surpasses other ground-based observatories in terms of detectability. With the 1D model petitCODE, we have self-consistently simulated the atmospheric pressure–temperature profiles, which are subsequently integrated into the 1D chemical kinetics model, VULCAN, to evolve the atmospheric chemistry. High-resolution spectra are obtained by performing line-by-line radiative transfer using petitRADTRANS. Finally, we use the resulting spectra to assess the detectability ( σ det ) of molecular bands, employing the ground-based noise simulator SPECTR. Utilizing cross-correlation spectroscopy, we have successfully demonstrated the robust consistency between our simulation study and real-time observations for both planets. ANDES excels overall in molecular detection, due to its enhanced instrumental architecture, reinforcing E-ELT’s importance for studying exoplanet atmospheres. Additionally, our theoretical simulations predict the detection of CO, NH 3 , and H 2 S in the WASP-76 b atmosphere with σ det > 3.