Lensing in the Blue III: Weak Lensing Shape Catalogs of 30 Merging Galaxy Clusters

TL;DR

This paper presents a weak gravitational lensing dataset of 30 merging galaxy clusters obtained from the balloon-borne SuperBIT telescope, demonstrating high-quality shape measurements and calibration techniques in near-space conditions.

Contribution

It introduces a novel weak-lensing shape catalog from SuperBIT, showcasing calibration and validation methods for unbiased shear measurements in a balloon-borne observational platform.

Findings

Achieved near diffraction-limited imaging above 98% of Earth's atmosphere.

Calibrated galaxy shapes with metacalibration for unbiased weak-lensing analysis.

Estimated shear bias of (1.1 ± 7.8)% using realistic simulations.

Abstract

We present the weak gravitational lensing dataset from the Super-pressure Balloon-Borne Imaging Telescope (SuperBIT), which imaged 30 galaxy clusters during its 45 night flight in April to May 2023. SuperBIT is a first-of-its-kind balloon-borne imaging telescope that achieved near diffraction-limited observations in near-space conditions above 98% of the Earth's atmosphere. We use the metacalibration algorithm to obtain calibrated galaxy shapes for our target clusters and several calibration fields, enabling unbiased reconstruction of the weak-lensing signal. We employ several diagnostics throughout the pipeline, including assessments of point-spread function (PSF) modeling residuals and their impact on weak-lensing measurements, as well as tests for correlations between galaxy shapes and measured galaxy and PSF properties. To assess the multiplicative shear bias of the pipeline, we analyze a parallel set of simulated images that incorporate the real observing conditions from the flight, including measured SuperBIT PSFs, observed sky backgrounds, and detector noise, yielding a bias of $(1.1 \pm 7.8)$~per~cent.