Analytical weak-lensing shear response of galaxy model fitting
Abstract
Galaxy model fitting is widely employed to estimate properties such as galaxy shape, size, and color. Understanding how the outputs of galaxy model fitting respond to weak-lensing shear distortions is crucial for accurate shear estimation and mitigating shear-related systematics in weak lensing image analyses. In this paper, we investigate how the fitted parameters - specifically flux, size, and shape - respond to weak-lensing shear distortions within the AnaCal framework. To achieve this, we introduce quintuple numbers, a novel algebraic system inspired by dual numbers from automatic differentiation. Quintuple numbers enable the propagation of shear response information throughout the entire model-fitting process by linking analytical pixel shear responses to those of the fitted parameters. We integrate quintuple numbers into the AnaCal framework to derive the shear responses of shapes estimated with model fitting and validate the pipeline using image simulations that include realistic blending. Our results demonstrate that the multiplicative bias remains below 0.003 for ground-based, oversampled images.
Related
- Weak-lensing Shear-Selected Galaxy Clusters from the Hyper Suprime-Cam Subaru Strategic Program: III. A precision cosmological sample enabled by optical confirmation
- Weak-Lensing Shear Response for Photometric Redshift-Based Tomographic Binning
- Weak lensing shear and aperture mass from linear to non-linear scales
- CHEX-MATE: AMALGAM weak-lensing analysis of 41 Planck Sunyaev--Zel'dovich-selected galaxy clusters
- Two-dimensional weak lensing shear for cluster mass, concentration, ellipticity and miscentering estimation
BibTeX
@article{li2026analytical,
title = {{Analytical weak-lensing shear response of galaxy model fitting}},
author = {Xiangchong Li},
journal = {The Open Journal of Astrophysics},
year = {2026},
month = oct,
doi = {10.33232/001c.172037},
url = {https://astro.theoj.org/article/172037-analytical-weak-lensing-shear-response-of-galaxy-model-fitting},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Analytical weak-lensing shear response of galaxy model fitting
AU - Xiangchong Li
PY - 2026
DA - 2026/10/02
JO - The Open Journal of Astrophysics
DO - 10.33232/001c.172037
UR - https://astro.theoj.org/article/172037-analytical-weak-lensing-shear-response-of-galaxy-model-fitting
AB - Galaxy model fitting is widely employed to estimate properties such as galaxy shape, size, and color. Understanding how the outputs of galaxy model fitting respond to weak-lensing shear distortions is crucial for accurate shear estimation and mitigating shear-related systematics in weak lensing image analyses. In this paper, we investigate how the fitted parameters - specifically flux, size, and shape - respond to weak-lensing shear distortions within the AnaCal framework. To achieve this, we introduce quintuple numbers, a novel algebraic system inspired by dual numbers from automatic differentiation. Quintuple numbers enable the propagation of shear response information throughout the entire model-fitting process by linking analytical pixel shear responses to those of the fitted parameters. We integrate quintuple numbers into the AnaCal framework to derive the shear responses of shapes estimated with model fitting and validate the pipeline using image simulations that include realistic blending. Our results demonstrate that the multiplicative bias remains below 0.003 for ground-based, oversampled images.
SN - 2565-6120
ER -