DESI-HSC-ACT data yield model-independent baryon gas fraction profiles at 17-sigma significance
Model-independent filtering of kSZ and weak-lensing signals around DESI galaxies detects baryon depletion at high significance and shows that current hydro simulations bracket but do not reproduce the observed gas distribution. The approach reduces reliance on parametric profiles for feedback calibration in cosmological analyses.
Researchers applied an identical radial aperture filter to galaxy-galaxy lensing convergence and velocity-weighted kSZ temperature maps from 0.26 < z < 1.1, directly producing the filtered gas fraction f_gas(R). The method recovers the ratio of ionized gas to total matter at projected radii from 0.1 to several Mpc. After beam-correction calibrated on simulations, the BGS sample shows 17.1-sigma depletion and the lowest-redshift LRG bin 15.8-sigma depletion relative to Omega_b/Omega_m.
Comparison with six hydrodynamical runs from Illustris, TNG, SIMBA and FLAMINGO demonstrates that no single feedback implementation matches the observed radial trend at all scales; data lie between the strongest (Illustris-1) and weaker prescriptions. The ratio remains stable when splitting by stellar mass or central/satellite status, supporting robustness.
Residual kSZ differences between NGC and SGC fields in one redshift bin flag possible unmodeled systematics. Future cross-checks with Simons Observatory or CMB-S4 maps at higher resolution will test whether the discrepancy is instrumental or astrophysical.
The measurement supplies a direct, simulation-independent anchor for baryonic feedback in weak-lensing cosmology, tightening the largest systematic uncertainty for Stage-IV surveys.
Liu et al.: Stacked kSZ-lensing ratio from Simons Observatory DR1 will confirm the same depletion slope to within 10% at 5 < R < 10 Mpc within 24 months of first light.
Sources (3)
- [1]Primary Source(https://arxiv.org/abs/2609.22466)
- [2]Supporting Source(https://arxiv.org/abs/2307.11157)
- [3]Supporting Source(https://arxiv.org/abs/2110.12738)