Annual Modulation of Cosmic Relic Neutrinos
  The cosmic neutrino background (CvB), produced about one second after the Big
Bang, permeates the Universe today. New technological advancements make
neutrino capture on beta-decaying nuclei (NCB) a clear path forward towards the
detection of the CvB. We show that gravitational focusing by the Sun causes the
expected neutrino capture rate to modulate annually. The amplitude and phase of
the modulation depend on the phase-space distribution of the local neutrino
background, which is perturbed by structure formation. These results also apply
to searches for sterile neutrinos at NCB experiments. Gravitational focusing is
the only source of modulation for neutrino capture experiments, in contrast to
dark-matter direct-detection searches where the Earth's time-dependent velocity
relative to the Sun also plays a role.
