A First Detection of the Acoustic Oscillation Phase Shift Expected from the Cosmic Neutrino Background

TL;DR

This paper reports the first detection of the phase shift in acoustic oscillations caused by the cosmic neutrino background, observed through its impact on the CMB temperature power spectrum, confirming a key prediction of cosmological models.

Contribution

It provides the first observational evidence of the acoustic phase shift induced by free-streaming neutrinos in the early universe.

Findings

Detected the phase shift in CMB temperature spectrum.

Confirmed the influence of cosmic neutrinos on acoustic oscillations.

Supports the standard cosmological model with neutrino background.

Abstract

The unimpeded relativistic propagation of cosmological neutrinos prior to recombination of the baryon-photon plasma alters gravitational potentials and therefore the details of the time-dependent gravitational driving of acoustic oscillations. We report here a first detection of the resulting shifts in the temporal phase of the oscillations, which we infer from their signature in the Cosmic Microwave Background (CMB) temperature power spectrum.