Measuring weak lensing correlations of Type Ia Supernovae

TL;DR

This study assesses the potential of detecting weak lensing correlations of Type Ia Supernovae using current and future surveys, predicting significant detections with LSST and promising constraints on cosmological parameters.

Contribution

It provides the first detailed analysis of weak lensing SN correlations using both analytical models and simulations, forecasting detectability and cosmological constraints with upcoming surveys.

Findings

SN auto-correlation detectable in LSST deep fields at ~6sigma

SN-galaxy cross-correlation highly detectable with signal-to-noise ~100

Potential to measure sigma_8 with 25% precision from LSST SNe

Abstract

We study the feasibility of detecting weak lensing spatial correlations between Supernova (SN) Type Ia magnitudes with present (Dark Energy Survey, DES) and future (Large Synoptic Survey Telescope, LSST) surveys. We investigate the angular auto-correlation function of SN magnitudes (once the background cosmology has been subtracted) and cross-correlation with galaxy catalogues. We examine both analytical and numerical predictions, the latter using simulated galaxy catalogues from the MICE Grand Challenge Simulation. We predict that we will be unable to detect the SN auto-correlation in DES, while it should be detectable with the LSST SN deep fields (15,000 SNe on 70 deg^2) at ~6sigma level of confidence (assuming 0.15 magnitudes of intrinsic dispersion). The SN-galaxy cross-correlation function will deliver much higher signal-to-noise, being detectable in both surveys with an integrated signal-to-noise of ~100 (up to 30 arcmin separations). We predict joint constraints on the matter density parameter (Omega_m) and the clustering amplitude (sigma_8) by fitting the auto-correlation function of our mock LSST deep fields. When assuming a Gaussian prior for Omega_m, we can achieve a 25% measurement of sigma_8 from just these LSST supernovae (assuming 0.15 magnitudes of intrinsic dispersion). These constraints will improve significantly if the intrinsic dispersion of SNe Ia can be reduced.