Speaker
Description
High-resolution Doppler-resolved spectroscopy has opened up a new window into the atmospheres of both transiting and non-transiting exoplanets. While the 'classical' cross-correlation approach is efficient for finding atomic and molecular species, it is quite limited with its inability to recover quantitative information on the atmosphere such as abundances and temperature profiles - the very information we need to understand planetary atmospheres! Here, I will outline a new retrieval framework based on a simple Gaussian likelihood coupled to a fast model-filtering technique that is critical to account for the common pre-processing steps performed on time-series spectra. I will demonstrate its use including the first retrievals of high-resolution transmission spectra, showcasing multiple detections of neutral and ionised metals (Fe, V, Mg, Cr, FeII, etc) in ultra-hot Jupiters, which in turn place robust and precise constraints on abundance ratios and temperature-pressure profiles, as well as directly constrain the mean line-profile. However, to fully realise the power of high-resolution spectroscopy - which is sensitive to winds and atmospheric escape - it is clear that we need to treat highly irradiated planets as 3D objects. This is incompatible with the requirement for ultra-fast forward model atmospheres which make high-resolution retrievals viable in the first place. I will finish by discussing some open questions and current limitations of high-resolution atmospheric retrievals, with the goal of encouraging discussion of the best routes forward.
