Quantifying the effects of spatial resolution and noise on galaxy
  metallicity gradients
  Metallicity gradients are important diagnostics of galaxy evolution, because
they record the history of events such as mergers, gas inflow and
star-formation. However, the accuracy with which gradients can be measured is
limited by spatial resolution and noise, and hence measurements need to be
corrected for such effects. We use high resolution (~20 pc) simulation of a
face-on Milky Way mass galaxy, coupled with photoionisation models, to produce
a suite of synthetic high resolution integral field spectroscopy (IFS)
datacubes. We then degrade the datacubes, with a range of realistic models for
spatial resolution (2 to 16 beams per galaxy scale length) and noise, to
investigate and quantify how well the input metallicity gradient can be
recovered as a function of resolution and signal-to-noise ratio (SNR) with the
intention to compare with modern IFS surveys like MaNGA and SAMI. Given
appropriate propagation of uncertainties and pruning of low SNR pixels, we show
that a resolution of 3-4 telescope beams per galaxy scale length is sufficient
to recover the gradient to ~10-20% uncertainty. The uncertainty escalates to
~60% for lower resolution. Inclusion of the low SNR pixels causes the
uncertainty in the inferred gradient to deteriorate. Our results can
potentially inform future IFS surveys regarding the resolution and SNR required
to achieve a desired accuracy in metallicity gradient measurements.
