Impact of Calibration Systematics on Dark Energy Constraints from LSST Type Ia Supernovae

TL;DR

This paper analyzes how calibration systematics in LSST's supernova measurements affect dark energy parameter estimates, emphasizing the importance of precise calibration for accurate cosmological constraints.

Contribution

It provides a comprehensive quantification of how passband calibration uncertainties bias dark energy parameters in LSST supernova analyses.

Findings

Linear passband tilts cause a 0.025σ shift in w0-wa parameters per 1% tilt.

Passband tilts increase the confidence contour area by about 5% per 100nm tilt.

Quadratic passband tilts have less conclusive effects, indicating need for further study.

Abstract

The Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST) will deliver an unprecedented Type Ia supernova (SN) sample, making photometric calibration systematics a dominant source of uncertainty in dark energy constraints. We perform a comprehensive analysis of calibration systematic effects in LSST, quantifying how uncertainties in the LSST passbands propagate into biases in SN distance moduli and, consequently, the dark energy equation of state parameters. Specifically, we examine how the inferred values and uncertainties of $w_0$ and $w_a$ shift as a function of the amplitude of passband systematics. For linear passband tilts, we find that the best-fit ($w_0$,$w_a$) shifts by $\sim$0.025$\sigma$ and the $w_0-w_a$ contour area increases by $\sim$5% for each 1%/100nm increase in tilt, while for quadratic passband tilts, our results are less conclusive and warrant further exploration. This analysis will help inform the calibration accuracy required for LSST to achieve its goals in constraining dark energy.