Type Ia Supernovae Selection and Forecast of Cosmology Constraints for the Dark Energy Survey

TL;DR

This paper evaluates photometric selection criteria for Type Ia supernovae in the Dark Energy Survey, aiming to optimize cosmological constraints by reducing contamination and improving the Figure of Merit.

Contribution

It introduces a novel analysis of core collapse contamination impact on supernova selection using the Figure of Merit in a simulated survey context.

Findings

Higher purity selection improves the Figure of Merit.

Optimal purity achieved at 98% with tighter cuts.

Both SALT2 and MLCS2k2 models benefit from refined selection criteria.

Abstract

We present the results of a study of selection criteria to identify Type Ia supernovae photometrically in a simulated mixed sample of Type Ia supernovae and core collapse supernovae. The simulated sample is a mockup of the expected results of the Dark Energy Survey. Fits to the MLCS2k2 and SALT2 Type Ia supernova models are compared and used to help separate the Type Ia supernovae from the core collapse sample. The Dark Energy Task Force Figure of Merit (modified to include core collapse supernovae systematics) is used to discriminate among the various selection criteria. This study of varying selection cuts for Type Ia supernova candidates is the first to evaluate core collapse contamination using the Figure of Merit. Different factors that contribute to the Figure of Merit are detailed. With our analysis methods, both SALT2 and MLCS2k2 Figures of Merit improve with tighter selection cuts and higher purities, peaking at 98% purity.