A Panchromatic View of the Early ISM: Modelling UV, Optical, and FIR Lines at z ~ 5 connecting ALMA & JWST
Enrico Veraldi (SISSA - International School for Advanced Studies, Trieste)
Tuesday 12/05/2026 @ 14:00, Sala Antonio Sollima (IV piano Battiferro)
Understanding the physical conditions of the ISM in the first galaxies is one of the key open questions in modern astrophysics. Deep surveys with ALMA and JWST now provide unprecedented access to multiple emission lines spanning the UV, optical, and far-infrared in galaxies at cosmic dawn, enabling a truly panchromatic view of the ISM. In this talk, I present a physically-motivated model that connects ALMA [CII] 158 ?m observations of 36 galaxies from the ALPINE survey at z~4–6 with predictions for rest-frame UV and optical lines (CIII] 1909Å, [OIII] 5007Å, H?) accessible with JWST. The model couples CLOUDY photoionization calculations — fed by both binary and single-star stellar population spectra — with an analytical framework that links galaxy-scale observables, such as the star-formation rate surface density, to ISM parameters including gas density n, ionization parameter U, metallicity Z, and burstiness k_s. I show that the choice of stellar population model, and in particular the inclusion of binary stars, has a significant impact on the predicted nebular line-to-[CII] ratios. I will close by presenting preliminary results from a Bayesian inference analysis applied to a subsample of 14 ALPINE-CRISTAL galaxies with available JWST observations from an approved follow-up program, recovering ISM properties and finding consistency with literature trends in the U–Z and n–z planes.