Galaxy And Mass Assembly (GAMA): The inferred mass--metallicity relation
  from z=0 to 3.5 via forensic SED fitting
  We analyse the metallicity histories of ~4,500 galaxies from the GAMA survey
at z<0.06 modelled by the SED-fitting code ProSpect using an evolving
metallicity implementation. These metallicity histories, in combination with
the associated star formation histories, allow us to analyse the inferred
gas-phase mass--metallicity relation. Furthermore, we extract the
mass--metallicity relation at a sequence of epochs in cosmic history, to track
the evolving mass--metallicity relation with time. Through comparison with
observations of gas-phase metallicity over a large range of redshifts, we show
that, remarkably, our forensic SED analysis has produced an evolving
mass--metallicity relationship that is consistent with observations at all
epochs. We additionally analyse the three dimensional mass--metallicity--SFR
space, showing that galaxies occupy a clearly defined plane. This plane is
shown to be subtly evolving, displaying an increased tilt with time caused by
general enrichment, and also the slowing down of star formation with cosmic
time. This evolution is most apparent at lookback times greater than 7 Gyr. The
trends in metallicity recovered in this work highlight that the evolving
metallicity implementation used within the SED fitting code ProSpect produces
reasonable metallicity results over the history of a galaxy. This is expected
to provide a significant improvement to the accuracy of the SED fitting
outputs.
