Nonlinear matter spectra in growing neutrino quintessence
  We investigate the nonlinear power spectra of density perturbations and
acoustic oscillations in growing neutrino quintessence. In this scenario, the
neutrino mass has a strong dependence on the quintessence field. The induced
coupling stops the evolution of the field when the neutrinos become
nonrelativistic, and triggers the transition to the accelerating phase of the
cosmological expansion. At redshifts around five, the neutrino fluctuations are
still linear and acoustic oscillations are present in the neutrino power
spectrum, induced by the acoustic oscillations in the baryonic and dark-matter
sectors. The neutrino perturbations become nonlinear at redshifts around three.
The mode coupling generated by the nonlinearities erases the oscillations in
the neutrino spectrum at some redshift above two. There is a potential danger
that at later times the influence of the gravitational potentials induced by
the neutrino inhomogeneities could erase the oscillations from the baryonic and
dark-matter spectra, making the scenario incompatible with observations. For
the scenario to be viable, the neutrino-induced gravitational potentials in the
range of baryonic acoustic oscillations should not grow to average values much
larger than 10^{-4}. The magnitude of the expected potentials is still not
known reliably, as the process of structure formation is poorly understood in
growing neutrino quintessence.
