Small scale aspects of warm dark matter : power spectra and acoustic oscillations

Details Small scale aspects of warm dark matter : power spectra and acoustic oscillations Small scale aspects of warm dark matter : power spectra and acoustic oscillations

2010-08-05

arxiv.org/abs/1008.0992v2

Phys.Rev.D83:043524,2011

Astronomy and Astrophysics

Astrophysics

Cosmology and Extragalactic Astrophysics

47 pages, 17 figures, section with comparison with Boltzmann codes

Scientific paper

10.1103/PhysRevD.83.043524

We provide a semi-analytic study of the small scale aspects of the power spectra of warm dark matter (WDM) candidates that decoupled while relativistic with arbitrary distribution functions. These are characterized by two widely different scales $k_{eq} \sim 0.01\,(\mathrm{Mpc})^{-1}$ and $k_{fs}= \sqrt{3}\,k_{eq}/2\,< V^2_{eq} >^{1/2} $ with $< V^2_{eq} >^{1/2} \ll 1 $ the velocity dispersion at matter radiation equality. Density perturbations evolve through three stages: radiation domination when the particle is relativistic and non-relativistic and matter domination. An early ISW effect during the first stage leads to an enhancement of density perturbations and a plateau in the transfer function for $k \lesssim k_{fs}$. An effective fluid description emerges at small scales which includes the effects of free streaming in initial conditions and inhomogeneities. The transfer function features \emph{WDM-acoustic oscillations} at scales $k \gtrsim 2 \,k_{fs}$. We study the power spectra for two models of sterile neutrinos with $m \sim \,\mathrm{keV}$ produced non-resonantly, at the QCD and EW scales respectively. The latter case yields acoustic oscillations on mass scales $\sim 10^{8}\,M_{\odot}$. Our results reveal a \emph{quasi-degeneracy} between the mass, distribution function and decoupling temperature suggesting caveats on the constraints on the mass of a sterile neutrino from current WDM N-body simulations and Lyman-$\alpha$ forest data. A simple analytic interpolation of the power spectra between large and small scales and its numerical implementation is given.

Affiliated with

Also associated with

No associations

Rating

Small scale aspects of warm dark matter : power spectra and acoustic oscillations does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Small scale aspects of warm dark matter : power spectra and acoustic oscillations, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Small scale aspects of warm dark matter : power spectra and acoustic oscillations will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-438573