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We apply fossil record techniques to the CALIFA sample to study how galaxies in the Local Universe have evolved in terms of their chemical content. We show how the stellar metallicity and the mass-metallicity relation (MZR) evolve through time for the galaxies in our sample and how this evolution varies when we divide them based on their mass, morphology, and star-forming status. We also check the impact of measuring the metallicity at the centre or the outskirts. We find the expected results that the most massive galaxies were enriched more quickly, and that the MZR was steeper at higher redshifts. However, once we separate the galaxies into morphology bins this behaviour is less clear, which suggests that morphology is a primary factor in determining how quickly a galaxy becomes enriched, but with mass determining the final enrichment. We also find that star-forming galaxies (SFGs) appear to be asymptotic in their chemical evolution; that is, the metallicity of SFGs of any mass is very similar at recent times unlike several Gyr ago. © 2021 The Author(s). ; We are grateful for the support of the Consejo Nacional de Ciencia y Tecnología (CONACYT) grants CB-285080 and FC-2016-01-1916, and funding from the Universidad Nacional Autónoma de México (UNAM) project PAPIIT-DGAPA-IN100519. LG was funded by the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 839090. This work has been partially supported by the Spanish grant PGC2018-095317-B-C21 within the European Funds for Regional Development (FEDER). We thank P. Tissera, N. Vale-Asari, and J. E. Beckman for their many helpful comments and discussion on the content of the paper. ; With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709. ; Peer reviewed

We present a novel method to retrieve the chemical structure of galaxies using integral field spectroscopy data through the stellar Metallicity Distribution Function (MDF). This is the probability distribution of observing stellar populations having a metallicity Z. We apply this method to a set of 550 galaxies from the CALIFA survey. We present the behaviour of the MDF as a function of the morphology, the stellar mass, and the radial distance. We use the stellar metallicity radial profiles retrieved as the first moment of the MDF, as an internal test for our method. The gradients in these radial profiles are consistent with the known trends: they are negative in massive early-type galaxies and tend to positive values in less massive late-type ones. We find that these radial profiles may not convey the complex chemical structure of some galaxy types. Overall, low mass galaxies (log M·/M· ≤ 10) have broad MDFs (σZ∼ 1.0 dex), with unclear dependence on their morphology. However this result is likely affected by under-represented bins in our sample. On the other hand, massive galaxies (log M·/M· ≥ 11) have systematically narrower MDFs (σZ≤ 0.2 dex). We find a clear trend whereby the MDFs at rk/Re > 1.5 have large variance. This result is consistent with sparse SFHs in medium/low stellar density regions. We further find there are multimodal MDFs in the outskirts (∼ 18%) and the central regions (∼ 40%) of galaxies. This behaviour is linked to a fast chemical enrichment during early stages of the SFH, along with the posterior formation of a metal-poor stellar population. © 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. ; We thank CONACYT FC-2016-01-1916 and CB-285080 projects and PAPIIT IN100519 project for support on this study. AMN specially thanks Carlos López-Cobá who selflessly shared his calculation of isophotal parameters for the sample used in this paper. AMN also thanks Jorge Barrera-Ballesteros for useful comments that improved an early version of this paper. AMN and EADL thank all Stellar Population Synthesis and Chemical Evolution group of the Instituto de Astronomía – UNAM for the help through the by-eye morphological classification. LG was funded by the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 839090. RGB acknowledges support from the State Agency for Research of the Spanish MCIU through the 'Center of Excellence Severo Ochoa' award to the Instituto de Astrofísica de Andalucía (SEV-2017-0709). ; Peer reviewed