Neutrino winds on the sky

TL;DR

This paper introduces a formalism to analyze how large-scale structures distort the relic neutrino density field, revealing a bispectrum signature that can help detect neutrino masses with future surveys.

Contribution

It develops a first-principles method to compute neutrino density distortions caused by structure motions, highlighting a novel bispectrum signal for neutrino mass detection.

Findings

Distortion affects neutrino-halo dynamics and cross-correlations.

Bispectrum signal peaks at squeezed configurations.

Future surveys can potentially detect this neutrino mass signature.

Abstract

We develop a first-principles formalism to compute the distortion to the relic neutrino density field caused by the peculiar motions of large-scale structures. This distortion slows halos down due to dynamical friction, causes a local anisotropy in the neutrino-CDM cross-correlation, and reduces the global cross-correlation between neutrinos and CDM. The local anisotropy in the neutrino-CDM cross-spectrum is imprinted in the three point cross-correlations of matter and galaxies, or the bispectrum in Fourier space, producing a signal peaking at squeezed triangle configurations. This bispectrum signature of neutrino masses is not limited by cosmic variance or potential inaccuracies in the modeling of complicated nonlinear and galaxy formation physics, and it is not degenerate with the optical depth to reionization. We show that future surveys have the potential to detect the distortion bispectrum.