The suppression of the matter power spectrum: strong feedback from X-ray gas mass fractions, kSZ effect profiles, and galaxy-galaxy lensing

Abstract Baryon feedback redistributes gas relative to the underlying dark matter distribution and suppresses the matter power spectrum on small scales, but the amplitude and scale dependence of this effect are uncertain. We constrain the impact of baryon feedback on the matter power spectrum by jointly analysing X-ray gas mass fractions from the eROSITA and HSC–XXL samples and SDSS/DESI+ACT kinetic Sunyaev–Zel’dovich (kSZ) effect profiles; the samples are characterised with galaxy-galaxy lensing and together span group and cluster masses ($13 < \log _{10} \frac{M_{500}}{\mathrm{M}_\odot ~h^{-1}} < 14$) at 0 < z < 1. Using the baryonification framework, our joint eROSITA and kSZ model gives precise constraints on the suppression of the matter power spectrum: $10\pm 2~{{\ \rm per\ cent}}$ at k = 1 h Mpc−1. The inferred gas profiles are more extended and the power suppression is stronger than predicted by the fiducial models of recent hydrodynamical simulation suites, including FLAMINGO and BAHAMAS. The HSC–XXL gas mass fractions, which the fiducial simulations were calibrated to reproduce, prefer more moderate power suppression than the kSZ and eROSITA data: $5\pm 4~{{\ \rm per\ cent}}$ at k = 1 h Mpc−1. With a simulated LSST Year 1 weak lensing analysis, we demonstrate a framework for next-generation surveys: calibrating feedback models with multi-wavelength gas observables to recover the small-scale statistical power of cosmic shear.