Unveiling Neutrino Halos with CMB Lensing

Understand

The existence of a cosmic neutrino background has been inferred indirectly from cosmological surveys through its effect on the linear-theory evolution of primordial density perturbations, as well as from measurements of the primordial abundances of light elements.

• Constraints on the masses of the three neutrino species imply that at least two of them move non-relativistically today.
• As a consequence, non-linear evolution of density perturbations results in the formation of neutrino halos around dark-matter halos.
• We study whether these neutrino halos can be detected in the foreseeable future through measurements of weak gravitational lensing of the cosmic microwave background, thus providing, possibly, the first beyond-linear-theory signature of cosmic neutrinos.