Cold-Mode Accretion: Driving the Fundamental Mass-Metallicity Relation
  at z~2
  We investigate the star formation rate (SFR) dependence on the stellar mass
and gas-phase metallicity relation at z=2 with MOSFIRE/Keck as part of the
ZFIRE survey. We have identified 117 galaxies (1.98 < z < 2.56), with
$8.9\leq$log(M/M$_{\odot}$)$\leq11.0$, for which we can measure gas-phase
metallicities. For the first time, we show discernible difference between the
mass-metallicity relation, using individual galaxies, when deviding the sample
by low ($<10$~M$_{\odot}$yr$^{-1}$) and high ($>10$~M$_{\odot}$yr$^{-1}$) SFRs.
At fixed mass, low star-forming galaxies tend to have higher metallicity than
high star-forming galaxies. Using a few basic assumptions, we further show that
the gas masses and metallicities required to produce the fundamental
mass--metallicity relation, and its intrinsic scatter, are consistent with
cold-mode accretion predictions obtained from the OWLS hydrodynamical
simulations. Our results from both simulations and observations are suggestive
that cold-mode accretion is responsible for the fundamental mass-metallicity
relation at $z=2$ and demonstrates the direct relationship between cosmological
accretion and the fundamental properties of galaxies.
