Reconstructing the shape of the non-linear matter power spectrum using CMB lensing and cosmic shear

Understand

We reconstruct the non-linear matter power spectrum $P(k)$ using a joint analysis of gravitational lensing of the cosmic microwave background (CMB) and lensing of galaxies.

• This reconstruction is motivated by the $S_8$ tension between early-universe CMB predictions and late-time observables.
• We use CMB lensing data from the Atacama Cosmology Telescope DR6 and cosmic shear data from the Dark Energy Survey (DES) Y3 release to perform a gravity-only (i.e.
• no baryonic feedback) fit to $P(k)$ in bins of wave-number, within $\rm{\Lambda CDM}$.