The Cosmic Infrared Background seen by ALMA

The origin of the Cosmic Infrared Background (CIB) is still poorly understood, and represents a challenge from both the theoretical and observational points of view. We analysed 18 ALMA continuum maps in band 6 and 7, with rms down to 7.8 $\mu$Jy, to estimate differential number counts down to 60 $\mu$Jy and 100 $\mu$Jy at $\lambda =$1.3 mm and $\lambda =$1.1 mm, respectively. Furthermore, the no-detection of faint sources in the deepest ALMA field enables us to set tight upper limits on the number counts down to 30 $\mu$Jy. We improved the source extraction method to detect sources down to S/N = 3.5. We detected 50 faint sources ($ 40 ~M_{\odot}/yr$. The differential number counts are in nice agreement with recent semi-analytical models of galaxy formation down to our faint fluxes, therefore supporting the galaxy evolutionary scenarios and assumptions made in these models.