Joint Astrophysical Colloquium
An infrared/submillimeter view on the universality of star-formation across cosmic time
Benjamin Magnelli (CEA Paris-Saclay)
Thursday 17/04/2025 @ 11:30, Sala Antonio Sollima (IV piano Battiferro)
Understanding the evolution of galaxies from the Big Bang to the present day is a difficult task, both observationally and theoretically. In this talk, I describe how, despite these challenges, we have been able to make significant progress in this field of research over the last 20 years, thanks in particular to the accurate measurement of the star formation rate, gas mass, and morphology of thousands of high-redshift galaxies using infrared/submillimetre observations from Spitzer, Herschel, ALMA, and JWST/MIRI. These measurements have led to the emergence of a new paradigm on the universality of star formation: the majority of stars in the Universe have formed in long, continuous phases, driven by the secular transformation into stars of gas accreted by galaxies from the cosmic web. In this talk, I will begin by summarizing our current knowledge of the cosmic density of star formation and molecular gas, and discuss how the simultaneous variation of these quantities with redshift (rising from early cosmic time, peaking at z~2, and decaying sharply to the present day) suggests a common mode of star formation, controlled by the availability of molecular gas in galaxies. I will then introduce the main sequence of star-forming galaxies and discuss how the study of galaxy properties in this context has led to the development of this new paradigm of a universal, secular mode of star formation across cosmic time, which is well described by so-called gas regulator models. I will conclude by describing some prospects in this area of research, based in particular on new observatories such as Euclid, SKA, CCAT-prime, and possibly AtLAST.