Robustness to systematics for future dark energy probes

TL;DR

This paper introduces a new robustness Figure of Merit for future dark energy surveys, accounting for systematic biases, and demonstrates its application to supernova and BAO surveys, highlighting differences in robustness.

Contribution

It develops a formalism to quantify robustness to systematics in dark energy probes using Fisher Matrix analysis, enhancing survey optimization.

Findings

SNIa are more robust to systematics than BAO in the considered scenarios.

Robustness depends on the alignment of systematic bias with degeneracy directions.

The new formalism can be applied to various future survey designs.

Abstract

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.