The 'glocal' drivers of the bimodality in galaxy stellar populations

I will present results on the spatially resolved stellar population (SP) properties of nearby galaxies over a broad range of masses and morphology, representative of the local Universe, obtained by joining integral field spectroscopy from CALIFA and broad-band images in a Bayesian framework with a highly complex SP modelling. Local scales have an important role in determining the properties of SPs, which result in local scaling relations linking age and metallicity with stellar mass surface density (Zibetti et al. 2017, 2020, +in prep.). Purely passive and old regions exist at any stellar mass surface density (mu*), while young regions become relatively older at increasing mu* and create a sequence that merges with the sequence of old and passive regions at mu*>5E3 Msun pc-2. Stellar metallicity is shown to follow a universal relation with mu*, but only at stellar masses >3E10 Msun. Total stellar mass, rather than stellar mass density, appears as the main drive r of galaxy bimodality.