Cold gas in cosmic space hosts emission of ionised carbon CII at a wavelength of 158 micron. This line is a powerful tracer of star formation activity and allows us to investigate the origin and evolution of galaxies deep in the primordial Universe. This is shown by the study of an international collaboration among scientists of the Astronomical Observatory of Trieste, the Max Planck Institute for Astrophysics (MPA) and The European Southern Observatory (ESO).By means of state-of-the-art numerical simulations, the researchers managed to follow consistently the formation of molecules in the early cosmic medium and the subsequent gas cooling and star formation events. In this way, they have been able to put first theoretical constraints on the evolution of the abundance of ionised carbon in the first Giga-year of life of the Universe.The study, in press on Astronomy and Astrophysics, predicts a correlation between the CII 158-micron line emission and the stellar mass of the host galaxy. This prediction is consistent, in the regime where observations are available, with the most recent determinations based on the analysis of ALMA data.“These results have been obtained thanks to a detailed implementation of the atomic processes in cold gas, in particular those linked to the ionised-carbon sub-mm line“ says Dr. Umberto Maio, a coauthor of the study and a researcher of the Italian National Institute for Astrophysics at the Astronomical Observatory of Trieste.Furthermore, gas cooling, heating and star formation activity taking place in the galaxy interstellar medium impact quantitatively the expected correlations between the main galaxy physical parameters, such as CII luminosity and star formation rate. This leads to the conclusion that an evolution in time of the empirical relations calibrated in the local Universe is possible.This work has been built on the extraordinary ALMA and JWST observations, two of the most advanced technological infrastructures available for scientific research. The findings of the study provide physical grounds to interpret primordial-galaxy detections in contemporary and future observations and to advance our knowledge on cosmic structure formation at early times.
ArXiv: https://arxiv.org/abs/2406.01277
Pictorial view of the CII 158-micron line emission as expected by the detailed theoretical models employed in the study.
