Robustness to systematics for future dark energy probes
  We extend the Figure of Merit formalism usually adopted to quantify the
statistical performance of future dark energy probes to assess the robustness
of a future mission to plausible systematic bias. We introduce a new robustness
Figure of Merit which can be computed in the Fisher Matrix formalism given
arbitrary systematic biases in the observable quantities. We argue that
robustness to systematics is an important new quantity that should be taken
into account when optimizing future surveys. We illustrate our formalism with
toy examples, and apply it to future type Ia supernova (SNIa) and baryonic
acoustic oscillation (BAO) surveys. For the simplified systematic biases that
we consider, we find that SNIa are a somewhat more robust probe of dark energy
parameters than the BAO. We trace this back to a geometrical alignement of
systematic bias direction with statistical degeneracy directions in the dark
energy parameter space.
