Gamma-ray luminosity/star-formation rate correlations in the context of the Cherenkov Telescope Array

Paper in proceeding, 2024

Star-forming galaxies (SFGs) are unique γ-ray emitters. The observed correlation between their non-thermal luminosity and their star-formation rate (SFR) strongly suggests that these γ rays result from the interactions of cosmic rays (CRs) injected by phenomena connected with the SFR, such as supernova remnants and massive star winds. These correlations provide insight into how global properties of galaxies like magnetic, velocity or density fields scale with the SFR. Here we investigate the effect of γ-ray absorption processes and cosmic-ray transport footprints in SFGs at very high energies (VHE) in terms of the luminosity–SFR correlations. With this purpose we extend an existing model that reproduces the non-thermal emission in SFGs from radio to GeV, by including γ-γ absorption process. We predict the correlation between the SFR and the luminosity in the Cherenkov Telescope Array (CTA) energy range, and explore how it is affected by the proton maximum energy and the absorption inside galaxies and en route to Earth.