Gerrit Farren and Alex Krolewski tell us about their work cross correlating the ACT lensing maps with unWISE galaxies. Their method is an update of earlier analyses using Planck lensing. Those earlier analyses were in tension with Planck primary CMB measurements, which was similar to e.g. cosmic shear, and other clustering measurements, at smaller scales.
Curiously, this new analysis reveals no tension with primary CMB. A re-analysis of Planck lensing cross unWISE, with updated assumptions and modelling, shows that Planck lensing is actually *also* not in tension with primary CMB (a combination of effects were responsible for removing the tension).
This analysis covers the large(ish) scale low(ish) redshift quadrant of the (k,z) space, suggesting that the origin of the S8 tension is likely to either be a very low redshift phenomenon, or scale dependent.
However Alex and Gerrit do note that a recent cross-correlation of Planck with DESI LRGs does seem to still indicate some tension at the same redshift and scales, so the dust hasn’t 100% settled on the large scale, low redshift quadrant.
Gerrit: https://www.maths.cam.ac.uk/person/gsf29
Cosmology Talks 