Portraying the missing baryonic mass at the cosmic noon: the contribution of CUBES

Abstract

AbstractThe cosmological and galactic missing baryon problems are briefly reviewed with a particular focus on the contributions to the baryonic census derived from the analysis of quasar absorption spectra. The CUBES spectrograph foreseen for the ESO VLT, with its exceptional efficiency ($$> 40$$ > 40 %), blue wavelength coverage ($$\lambda \simeq 300-405$$ λ ≃ 300 - 405 nm) and intermediate resolution ($$R\simeq 24,000$$ R ≃ 24 , 000 ) will allow us to tackle this issue with two approaches: using H i Lyman-$$\alpha$$ α lines at $$z \simeq 1.5-2.3$$ z ≃ 1.5 - 2.3 , just after the peak of star formation, and using O vi absorbers at $$z \simeq 1.9-2.9$$ z ≃ 1.9 - 2.9 , at the cosmic noon. In both cases, in order to derive the baryonic masses it will be necessary to acquire also higher-resolution spectra of the same target quasars to cover the region at longer wavelengths. We simulate the observations with the CUBES E2E simulator considering a sample of 40 bright quasars at redshifts $$z_\mathrm{em}\sim 2-3$$ z em ∼ 2 - 3 observed for a total time of $$\sim 13$$ ∼ 13 h to reach a signal-to-noise ratio of $$\sim 15$$ ∼ 15 in the H i Lyman-$$\alpha$$ α , O vi forests.