Kavli Affiliate: Blake Sherwin
| First 5 Authors: Karen Perez Sarmiento, Alex Laguë, Mathew Madhavacheril, Bhuvnesh Jain, Blake Sherwin
| Summary:
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 $rm{Lambda
CDM}$. We find that with DES cosmic shear data alone, $P(k)$ departs from the
early-universe CMB prediction on all scales. The joint fit with CMB lensing is
consistent on large scales $k<0.2 ;{rm Mpc}^{-1}$ but shows a $sim 2 sigma$
deviation from scale-independence when extending to $k = 10 ;h/mathrm{Mpc}$.
We compare our agnostic $P(k)$ reconstruction to baryonic feedback models and
non-standard dark matter models: reasonable variations of both scenarios can
recover the shape and amplitude of the suppression. We discuss the advances
needed to disentangle these physical effects with a full mapping of $P(k,z)$.
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