7-9 September 2022
Leibniz Institute for Astrophysics Potsdam (AIP)
Europe/Berlin timezone

From cross-correlations to likelihoods: What can we do with high-resolution transmission spectroscopy?

8 Sep 2022, 09:45
15m
Lecture Hall (Leibniz Institute for Astrophysics Potsdam (AIP))

Lecture Hall

Leibniz Institute for Astrophysics Potsdam (AIP)

An der Sternwarte 16 14482 Potsdam, Germany
Oral presentation Main conference

Speaker

Prof. Neale Gibson (Trinity College Dublin)

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.

Primary author

Prof. Neale Gibson (Trinity College Dublin)

Presentation Materials

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