Cross-Calibration of Cluster Mass-Observables

TL;DR

This paper develops a formalism for combining multiple cluster observation techniques to improve dark energy constraints, demonstrating that cross-calibration significantly enhances parameter precision and reduces sensitivity to observational thresholds.

Contribution

It introduces a formalism for cross-calibrating cluster mass-observables, improving dark energy parameter constraints by combining different observational methods.

Findings

Cross-calibration doubles the constraint precision on Omega_{DE} and w.

The approach reduces sensitivity to mass threshold and redshift range variations.

Correlation between different observables is well constrained without extra priors.

Abstract

This paper is a first step towards developing a formalism to optimally extract dark energy information from number counts using multiple cluster observation techniques. We use a Fisher matrix analysis to study the improvements in the joint dark energy and cluster mass-observables constraints resulting from combining cluster counts and clustering abundances measured with different techniques. We use our formalism to forecast the constraints in Omega_{DE} and w from combining optical and SZ cluster counting on a 4000 sq. degree patch of sky. We find that this cross-calibration approach yields ~2 times better constraints on Omega_{DE} and w compared to simply adding the Fisher matrices of the individually self-calibrated counts. The cross-calibrated constraints are less sensitive to variations in the mass threshold or maximum redshift range. A by-product of our technique is that the correlation between different mass-observables is well constrained without the need of additional priors on its value.