English

FLAMINGO: Baryonic effects on the weak lensing scattering transform

Cosmology and Nongalactic Astrophysics 2025-10-14 v1

Abstract

The scattering transform is a wavelet-based statistic capable of capturing non-Gaussian features in weak lensing (WL) convergence maps and has been proven to tighten cosmological parameter constraints by accessing information beyond two-point functions. However, its application in cosmological inference requires a clear understanding of its sensitivity to astrophysical systematics, the most significant of which are baryonic effects. These processes substantially modify the matter distribution on small to intermediate scales (k0.1hMpc1k\gtrsim 0.1\,h\,\mathrm{Mpc}^{-1}), leaving scale-dependent imprints on the WL convergence field. We systematically examine the impact of baryonic feedback on scattering coefficients using full-sky WL convergence maps with Stage IV survey characteristics, generated from the FLAMINGO simulation suite. These simulations include a broad range of feedback models, calibrated to match the observed cluster gas fraction and galaxy stellar mass function, including systematically shifted variations, and incorporating either thermal or jet-mode AGN feedback. We characterise baryonic effects using a baryonic transfer function defined as the ratio of hydrodynamical to dark-matter-only scattering coefficients. While the coefficients themselves are sensitive to both cosmology and feedback, the transfer function remains largely insensitive to cosmology and shows a strong response to feedback, with suppression reaching up to 10%10\% on scales of k0.1hMpc1k\gtrsim 0.1\,h\,\mathrm{Mpc}^{-1}. We also demonstrate that shape noise significantly diminishes the sensitivity of the scattering coefficients to baryonic effects, reducing the suppression from 210  %\sim 2 - 10 \;\% to 1  %\sim 1\;\%, even with 1.5 arcmin Gaussian smoothing. This highlights the need for noise mitigation strategies and high-resolution data in future WL surveys.

Keywords

Cite

@article{arxiv.2510.09761,
  title  = {FLAMINGO: Baryonic effects on the weak lensing scattering transform},
  author = {Mariia Marinichenko and Marcel P. van Daalen and Elena Sellentin and Jeger C. Broxterman and Matthieu Schaller and Joop Schaye},
  journal= {arXiv preprint arXiv:2510.09761},
  year   = {2025}
}

Comments

17 pages; 9 figures

R2 v1 2026-07-01T06:30:15.843Z