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

Abstract

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 $k_{fs}=\sqrt{3}{k}_{eq}/2<V_{eq}^2{>}^{1/2}$ with $<V_{eq}^2{>}^{1/2}\ll 1$ 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 $k\gtrsim 2k_{fs}$. 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.

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

References in corpus (33)

• The Observed properties of Dark Matter on small spatial scales
• The Universal Rotation Curve of Spiral Galaxies. II The Dark Matter Distribution out to the Virial Radius
• Sterile neutrinos, dark matter, and the pulsar velocities in models with a Higgs singlet
• Can sterile neutrinos be the dark matter?
• The kinematic status and mass content of the Sculptor dwarf spheroidal galaxy
• Dark-matter sterile neutrinos in models with a gauge singlet in the Higgs sector
• Can sterile neutrinos be ruled out as warm dark matter candidates?
• Opening a new window for warm dark matter
• How cold is cold dark matter? Small scales constraints from the flux power spectrum of the high-redshift Lyman-alpha forest
• Relic keV sterile neutrinos and reionization
• Direct X-ray Constraints on Sterile Neutrino Warm Dark Matter
• Constraints on Sterile Neutrino Dark Matter
• The emptiness of voids: yet another over-abundance problem for the LCDM model
• Restrictions on parameters of sterile neutrino dark matter from observations of galaxy clusters
• Constraints on dark matter particles from theory, galaxy observations and N-body simulations
• Massive Neutrinos in Cosmology: Analytic Solutions and Fluid Approximation
• The distribution function of dark matter in massive haloes
• Searching for dark matter in X-rays: how not to check the dark matter origin of a spectral feature
• Clustering properties of a sterile neutrino dark matter candidate
• Analyze This! A Cosmological Constraint Package for CMBEASY
• Search for the light dark matter with an X-ray spectrometer
• Small-scale structure formation properties of chilled sterile neutrinos as dark matter
• Sterile neutrinos as subdominant warm dark matter
• LambdaCDM Halo Density Profiles: where do actual halos converge to NFW ones?
• Galaxy Size Problem at z=3: Simulated Galaxies Are Too Small
• Constraining Warm Dark Matter using QSO gravitational lensing
• Sterile neutrinos
• Is gravitino still a warm dark matter candidate?
• Free streaming in mixed dark matter
• Collider signatures of sterile neutrinos in models with a gauge-singlet Higgs
• Precision Cosmology: Successes and Challenges
• Detecting sterile dark matter in space
• Accounting for the Unresolved X-ray Background with Sterile Neutrino Dark Matter

Cited by in corpus (3)

• Warm dark matter at small scales: peculiar velocities and phase space density
• Reconciling thermal leptogenesis with the gravitino problem in SUSY models with mixed axion/axino dark matter
• Consistent initial data for CMD perturbations