Impact of galaxy intrinsic alignments on non-Gaussian weak lensing statistics for modified gravity
Abstract
Non-Gaussian weak lensing statistics improve the constraining power of cosmic shear data by harvesting information unavailable to two-point statistics, within and beyond the GR+ΛCDM scenario. Dark energy, total neutrino mass and deviations from GR have all been shown to be better measured with non-Gaussian lensing probes, in simplified conditions. Previous studies typically overlook the impact of secondary lensing signals, which can be large and therefore can significantly affect the conclusions. Here we investigate the impact on measurements of cosmological and modified gravity parameters in the presence of galaxy intrinsic alignments. We focus on the power spectra, lensing PDF, peaks and minima counts, void abundance and void profiles. These non-Gaussian statistics are measured from the MGLenS mock weak lensing maps, in which three cosmological parameters and one gravitational parameter are varied, either in the f(R) or nDGP scenario, assuming Stage-IV lensing survey precision. These simulations are infused with the non-linear linear alignment model, allowing us to build emulators for each statistic with or without IA, and to study biases in full MCMC analyses. We show that in the absence of IA, lensing void profiles and abundance generally yield the highest Figure of Merit in the S8 − fR0 and S8 − H0 rc planes, at times improving by an order of magnitude over two-point functions. When IA is unaccounted for, major parameter biases are observed in the cosmology sector, while the modified gravity sector is relatively unaffected. We find that these biases can generally be flagged from poor goodness-of-fit measurements, except for a few cases where IA can fully masquerade as a lower Ωm and lower S8 cosmology.
Related
- Extracting intrinsic alignments in the Dark Energy Survey’s year 1 data, using the self-calibration method and LSST-DESC tools
- Model-Independent Assessments of Tidal Alignment and Density-Weighting Dependence in Galaxy Intrinsic Alignments
- Baryonic feedback and intrinsic alignments in profile: a frequentist view of DES Y3 cosmic shear
- First application of weak lensing peak steepness statistics to HSC Y1 data: effectively probing halo density profiles
- Mitigating baryonic effects in weak lensing with higher-order statistics
BibTeX
@misc{chawla2026impact,
title = {{Impact of galaxy intrinsic alignments on non-Gaussian weak lensing statistics for modified gravity}},
author = {Mehar Chawla and Christopher T. Davies and Joachim Harnois-Déraps and Baojiu Li and Joseph J. Mohr and Bipradeep Saha},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.12038},
eprint = {2609.12038},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.12038},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Impact of galaxy intrinsic alignments on non-Gaussian weak lensing statistics for modified gravity
AU - Mehar Chawla
AU - Christopher T. Davies
AU - Joachim Harnois-Déraps
AU - Baojiu Li
AU - Joseph J. Mohr
AU - Bipradeep Saha
PY - 2026
DA - 2026/09/10
PB - arXiv
DO - 10.48550/arxiv.2609.12038
UR - https://arxiv.org/abs/2609.12038
AB - Non-Gaussian weak lensing statistics improve the constraining power of cosmic shear data by harvesting information unavailable to two-point statistics, within and beyond the GR+ΛCDM scenario. Dark energy, total neutrino mass and deviations from GR have all been shown to be better measured with non-Gaussian lensing probes, in simplified conditions. Previous studies typically overlook the impact of secondary lensing signals, which can be large and therefore can significantly affect the conclusions. Here we investigate the impact on measurements of cosmological and modified gravity parameters in the presence of galaxy intrinsic alignments. We focus on the power spectra, lensing PDF, peaks and minima counts, void abundance and void profiles. These non-Gaussian statistics are measured from the MGLenS mock weak lensing maps, in which three cosmological parameters and one gravitational parameter are varied, either in the f(R) or nDGP scenario, assuming Stage-IV lensing survey precision. These simulations are infused with the non-linear linear alignment model, allowing us to build emulators for each statistic with or without IA, and to study biases in full MCMC analyses. We show that in the absence of IA, lensing void profiles and abundance generally yield the highest Figure of Merit in the S_8 − f_R0 and S_8 − H_0 r_c planes, at times improving by an order of magnitude over two-point functions. When IA is unaccounted for, major parameter biases are observed in the cosmology sector, while the modified gravity sector is relatively unaffected. We find that these biases can generally be flagged from poor goodness-of-fit measurements, except for a few cases where IA can fully masquerade as a lower Ω_m and lower S_8 cosmology.
ER -