Ariel-IT end-to-end exercise from the astrophysical scene to planetary spectra: simulations and retrieval

The forthcoming Ariel space mission will conduct the first spectroscopic survey of the atmospheres of hundreds of exoplanets in the visible and infrared bands of the electromagnetic spectrum. The mission is currently in Phase C and a Dry-Run exercise is ongoing to assess early preparedness and highlight key areas for further work ahead of launch in 2029. The Ariel-IT community has set up an end-to-end procedure from target identification to simulated primary transit observations and retrieval. The current focus is on a sample of hot Jupiters and planets orbiting active stars, with key activities including determination of stellar and planetary properties, planetary formation and evolution models, star-planet interaction, atmospheric evolution, and spectral synthesis. These simulations are passed as inputs to the latest version of the exoplanet observation simulator, ExoSim2, alongside the Ariel payload description and the PSFs vs wavelength for each instrument and focal plane generated with PAOS, a generic open-source physical optics simulator. ExoSim2 produces photometric and spectroscopic timelines of a simulated Ariel observation in the time domain, including the effects of stellar activity and jitter in the spacecraft's line of sight, a source of disturbance when measuring the spectra of exoplanet atmospheres. Our preliminary results for WASP-69b showcase the ability to achieve photon noise-limited observations across the entire Ariel spectrum post-processing and the possibility to discriminate between different input atmospheric compositions in the studied cases. Current limitations will be discussed along with the next steps needed to complete the analysis of our sample.