Chemical evolution history of MaNGA galaxies
  We show the results of a study using the spectral synthesis technique study
for the full MaNGA sample showing their Chemical Enrichment History (ChEH) as
well as the evolution of the stellar mass-metallicity relation (MZR) over
cosmic time. We find that the more massive galaxies became enriched first and
the lower mass galaxies did so later, producing a change in the MZR which
becomes shallower in time. Separating the sample into morphology and
star-forming status bins some particularly interesting results appear: The mass
dependency of the MZR becomes less relevant for later morphological types, to
the extent that it inverts for Sd/Irr galaxies, suggesting that morphology is
at least as important a factor as mass in chemical evolution. The MZR for the
full sample shows a flattening at the high-mass end and another at the low-mass
range, but the former only appears for retired galaxies while the latter only
appears for star-forming galaxies. We also find that the average metallicity
gradient is currently negative for all mass bins but for low mass galaxies it
was inverted at some point in the past, before which all galaxies had a
positive gradient. We also compare how diverse the ChEHs are in the different
bins considered as well as what primarily drives the diversity: How much
galaxies become enriched or how quickly they do so.
