Galaxy ISM across cosmic time: from high-redshift massive galaxies to low-redshift dwarfs
by
Sala Jappelli
Osservatorio
ABSTRACT
Molecular hydrogen (H2) is a fundamental component of galaxies, being the most abundant element in molecular clouds, where stars form, and an important source of radiative cooling at low temperatures. From an observational point of view, directly observing H2 is hard, especially at high redshift, and more easily observable tracers as CII or CO have been commonly used so far to infer the properties of the interstellar medium (ISM) across different cosmic epochs. In particular, thanks to the ALMA telescope, we started to collect data of the CII emission in high-redshift galaxies with unprecedented resolution, and by using scaling relations between CII and SFR, we have been able to infer the molecular gas distribution in these systems and its kinematics. Now, with the advent of JWST, we will be also able to directly probe the stellar distribution in these systems, and also nebular lines associated to recent star formation. In order to accurately interpret these unprecedented observations, a detailed theoretical framework is necessary. Unfortunately, the large majority of numerical simulations on galactic and cosmological scales to date still lacks the ability to self-consistently follow the formation and dissociation of H2 and metal elements in the ISM, typically associated to line emission in the far infrared, and must rely on pre-calibrated sub-grid models to compare results with observations. This limitation is becoming even more severe if we consider that JWST will also probe nebular lines, which require a detailed modelling of warmer gas. I will present a series of numerical studies devoted to the study of the ISM in high (and low) redshift galaxies, in which the evolution of H2 and of the main coolants of the cold ISM (C,O,Si) is followed via non-equilibrium chemistry, including gas and dust shielding, H2 self-shielding, star formation, supernova feedback, and extragalactic and local stellar radiation. I will discuss in particular the importance of an accurate modelling of the ISM for a proper comparison with observations, the role of metallicity in the evolution of the CII-SFR relation across cosmic epochs, and the interplay between BHs and the ISM in high-redshift galaxies.
The seminar will be in Aula Jappelli and on line:
Seminario: Alessandro Lupi
Mercoledì, 21 dicembre · 14:30 – 15:30
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Giovanni Carraro