Topic: baryonic feedback

Baryonic feedback introduces substantial uncertainty into cosmological inference from weak lensing. Henry Liu presents measurements of radial gas fractions around DESI galaxies that avoid assuming parametric gas profiles. The method combines galaxy-galaxy lensing with the kinematic Sunyaev–Zel’dovich effect, using a modified kSZ filter matched to the lensing delta-Sigma observable to estimate gas fractions directly. The analysis joins DESI DR2 Bright Galaxy Survey and luminous-red-galaxy samples with ACT DR6 microwave-background maps and HSC Y3 shear data. Gas fractions are suppressed at smal

Jared Siegel presents measurements that address two limitations of weak-lensing cosmology: intrinsic galaxy alignments and baryonic feedback. More than two million DESI galaxies and four lensing surveys provide alignment measurements across colour, luminosity, stellar mass and redshift. Combining Sunyaev–Zel’dovich profiles, eROSITA gas fractions and galaxy–galaxy lensing then constrains how feedback redistributes matter in groups and clusters at redshifts between zero and one. The results indicate stronger gas expulsion beyond virial radii than many simulations predict, reducing small-scale m