http://arxiv.org/abs/2203.13103
We study the linear effects of massive neutrinos on the matter density fluctuations on both large and small scales by solving the fluid equations that are obtained from Boltzmann hierarchy. These equations set the evolution of density and velocity perturbations of cold dark matter and neutrinos after the latter become non-relativistic. Due to the free-streaming effects, the massive neutrinos suppress the total matter power spectrum on small scales while leaving the large scales untouched. Approximating the neutrino distribution function as peaked at one value gives an equation of state that can then be used in an analytic solution of the fluid equations. We then test the validity of fluid approximation with full Boltzmann solvers such as \textsc{class}. We also comment on the effects of dark energy on our results.
F. Kamalinejad and Z. Slepian
Fri, 25 Mar 22
5/46
Comments: N/A