Generating and analyzing constrained dark energy equations of state and systematics functions

Abstract

Some functions entering cosmological analysis, such as the dark energy equation of state or systematic uncertainties, are unknown functions of redshift. To include them without assuming a particular form, we derive an efficient method for generating realizations of all possible functions subject to certain bounds or physical conditions, e.g. $w\ensuremath{\in}[\ensuremath{-}1,+1]$ as for quintessence. The method is optimal in the sense that it is both pure and complete in filling the allowed space of principal components. The technique is applied to propagation of systematic uncertainties in supernova population drift and dust corrections and calibration through to cosmology parameter estimation and bias in the magnitude-redshift Hubble diagram. We identify specific ranges of redshift and wavelength bands where the greatest improvements in supernova systematics due to population evolution and dust correction can be achieved.