Non-linear evolution of suppressed dark matter primordial power spectra

Abstract

We address the degree and rapidity of generation of small‐scale power over the course of structure formation in cosmologies where the primordial power spectrum is strongly suppressed beyond a given wavenumber. We first summarize the situations where one expects such suppressed power spectra and point out their diversity. We then employ an exponential cut‐off, which characterizes warm dark matter (WDM) models, as a template for the shape of the cut‐off and focus on damping scales ranging from 106 to 109 h−1 M⊙. Using high‐resolution simulations, we show that the suppressed part of the power spectrum is quickly (re)generated and catches up with both the linear and the non‐linear evolution of the unsuppressed power spectrum. From z= 2 onwards, a power spectrum with a primordial cut‐off at 109 h−1 M⊙ becomes virtually indistinguishable from an evolved cold dark matter (CDM) power spectrum. An attractor such as that described in Zaldarriaga, Scoccimarro & Hui for power spectra with different spectral indices also emerges in the case of truncated power spectra. Measurements of z∼ 0 non‐linear power spectra at ∼100 h−1 kpc cannot rule out the possibility of linear power spectra damped below ∼109 h−1 M⊙. Therefore, WDM or scenarios with similar features should be difficult to exclude in this way.

Cosmology of fermionic dark matter

“…In this case the resulting mass range is at most 1.8 eV ≤ m ≤ 53 eV, where the upper bound scales linearly with g s ef f (T Dec ). In figure 13 we show the combined results on g A free streaming mass of more than ∼ 10 9 solar masses is excluded for warm dark matter as found by [41]. The region excluded by this constraint is the area with the vertical pattern.…”

“…One can see here that the velocity dispersion (or the speed of sound) drops like for an ordinary warm dark matter scenario (Ref. [40,41,44,45]) contrary to the generalized Chaplygin gas which has a late time growing speed of sound. Now inserting the velocity dispersion into eq.…”

Constraints on warm dark matter from weak lensing in anomalous quadruple lenses

“…One is the quick regeneration of the suppressed power of WDM models and the catching up with the linear and non-linear power of the CDM models (Boehm et al 2005;Schneider et al 2012). This effect might make WDM models difficult to exclude using QSO-galaxy lensing systems.…”

Constraining dark matter-neutrino interactions using the CMB and large-scale structure

“…The general assumption is that DM consists of cold, massive particles (CDM). However, recent work has shown that small couplings with Standard Model particles (in particular, neutrinos [5][6][7][8][9], photons [10][11][12][13] and baryons [14][15][16]) cannot yet be ruled out using cosmological data alone and are indeed expected in several extensions of the Standard Model e.g. Refs.…”