The impact of baryons on weak lensing statistics as a function of halo mass and radius
Published in arXiv preprint, 2026
Upcoming weak lensing surveys such as those by Euclid, LSST, and Roman require percent-level control over systematic effects. A common approach to mitigating baryonic effects uses semi-analytic baryon correction models (BCMs) that modify halo profiles in dark matter-only simulations, calibrated to statistics from hydrodynamic simulations. We investigate the limits of this approach by progressively replacing larger regions around halos of decreasing mass in DMO simulations with their hydrodynamical counterparts. We compare multiple statistics — the matter and weak-lensing power spectra, peak counts, minima, one-point PDFs, and Minkowski functionals — and find that replacing all halos with M >= 10^12 h^-1 M_sun out to r <= 5 R_200 recovers ~90% of the baryonic suppression. Each statistic has distinct sensitivities to baryons. We show that BCMs applied to massive halos make two cancelling “mistakes”: they underpredict core masses and compensate by overpredicting baryonic impacts at larger radii. We provide a framework for diagnosing critical mass/radius regions in baryonic modeling for next-generation BCMs.
Recommended citation: M. E. Lee, Z. Haiman, S. Genel (2026) "The impact of baryons on weak lensing statistics as a function of halo mass and radius." arXiv:2603.11815.
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