A relationship between specific star formation rate and metallicity
  gradient within z=1 galaxies from KMOS-HiZELS
  We have observed a sample of typical z=1 star forming galaxies, selected from
the HiZELS survey, with the new KMOS near-infrared, multi-IFU instrument on the
VLT, in order to obtain their dynamics and metallicity gradients. The majority
of our galaxies have a metallicity gradient consistent with being flat or
negative (i.e. higher metallicity cores than outskirts). Intriguingly, we find
a trend between metallicity gradient and specific star formation rate (sSFR),
such that galaxies with a high sSFR tend to have relatively metal-poor centres,
a result which is strengthened when combined with datasets from the literature.
This result appears to explain the discrepancies reported between different
high redshift studies and varying claims for evolution. From a galaxy evolution
perspective, the trend we see would mean that a galaxy's sSFR is governed by
the amount of metal poor gas that can be funnelled into its core, triggered
either by merging or through efficient accretion. In fact merging may play a
significant role as it is the starburst galaxies at all epochs, which have the
more positive metallicity gradients. Our results may help to explain the origin
of the fundamental metallicity relation, in which galaxies at a fixed mass are
observed to have lower metallicities at higher star formation rates, especially
if the metallicity is measured in an aperture encompassing only the central
regions of the galaxy. Finally, we note that this study demonstrates the power
of KMOS as an efficient instrument for large scale resolved galaxy surveys.
