On the metallicity and age gradients of the ETGs in 12 clusters from MUSE resolved spectroscopy

Cluster cores are rich of red and old galaxies. Here we find the fossil imprints of their formation and evolution mechanisms in stellar metallicity gradients. By taking advantage of an exquisite coupling of HST and deep MUSE observations we characterised the spectroscopic properties of 272 early-type galaxies in the cores of 12 galaxy clusters at redshifts ranging from z~0.3 up to z~0.5. The favourable combination of the redshift of these clusters with the angular extension and the spatial resolution of the MUSE mosaics allowed us to directly measure the stellar age and metallicity gradients at unprecedented galactocentric distances (for a spatially resolved spectroscopic analysis). In agreement with a merging scenario and consistently with previous findings, our results confirm a strong and negative mean stellar metallicity gradient. We also found that the observed age gradient is negligible. Additionally, various correlations were tested and the strongest dependence was confirmed on the velocity dispersion, with a downturn of the stellar metallicity gradient for the most massive galaxies in our sample. To ease the process of exploring and analysing the MUSE mosaics, we took advantage of an unpublished Python GUI which has been under development in the last months and will be soon made publicly available. Such a tool is extremely useful for the analysis of MUSE data and will be of great help for future spatially resolved spectroscopy in general IFU-based studies