Impact of a Warm Dark Matter late-time velocity dispersion on large-scale structures

Abstract

We investigate whether the late-time (at $z\le 100$) velocity dispersion expected in Warm Dark Matter scenarios could have some effect on the cosmic web (i.e., outside of virialized halos). We consider effective hydrodynamical equations, with a pressurelike term that agrees at the linear level with the analysis of the Vlasov equation. Then, using analytical methods, based on perturbative expansions and the spherical dynamics, we investigate the impact of this term for a 1 keV dark matter particle. We find that the late-time velocity dispersion has a negligible effect on the power spectrum on perturbative scales and on the halo mass function. However, it has a significant impact on the probability distribution function of the density contrast at $z\sim 3$ on scales smaller than $0.1h^{-1}$Mpc, which correspond to Lyman-$\alpha$ clouds. Finally, we note that numerical simulations should start at $z_i\ge 100$ rather than $z_i\le 50$ to avoid underestimating gravitational clustering at low redshifts.

12 pages

References in corpus (15)

• Cosmological Constraints from the SDSS Luminous Red Galaxies
• The Luminosity Function of the Milky Way Satellites
• Can sterile neutrinos be the dark matter?
• Cosmological puzzle resolved by stellar feedback in high redshift galaxies
• Realistic sterile neutrino dark matter with keV mass does not contradict cosmological bounds
• Constraints on Sterile Neutrino Dark Matter
• On the Structure of Dark Matter Halos at the Damping Scale of the Power Spectrum with and without Relict Velocities
• Massive Neutrinos in Cosmology: Analytic Solutions and Fluid Approximation
• Large-N expansions applied to gravitational clustering
• Small scale aspects of warm dark matter : power spectra and acoustic oscillations
• Is gravitino still a warm dark matter candidate?
• Structure Formation in Modified Gravity Scenarios
• The dark matter transfer function: free streaming, particle statistics and memory of gravitational clustering
• Expansion schemes for gravitational clustering: computing two-point and three-point functions
• Warm dark matter at small scales: peculiar velocities and phase space density

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• Kinematic effects of the velocity fluctuations for dark halos population in LCDM model