Dark acoustic oscillations: imprints on the matter power spectrum and the halo mass function

Abstract

Many non-minimal dark matter scenarios lead to oscillatory features in the matter power spectrum induced by interactions either within the dark sector or with particles from the standard model. Observing such dark acoustic oscillations would therefore be a major step towards understanding dark matter. We investigate what happens to oscillatory features during the process of nonlinear structure formation. We show that at the level of the power spectrum, oscillations are smoothed out by nonlinear mode coupling, gradually disappearing towards lower redshifts. In the halo mass function, however, the oscillatory features remain visible until the present epoch. As a consequence, dark acoustic oscillations could be detectable in observations that are either based on the halo mass function or on the high-redshift power spectrum. We investigate the effect of such features on different observables, namely, the cluster mass function, the stellar-to-halo mass relation, and the Lyman-α flux power spectrum. We find that oscillatory features remain visible in all of these observables, but they are very extended and of low amplitude, making it challenging to detect them as distinct features in the data.

Enhanced Small-Scale Structure in the Cosmic Dark Ages

“…While we might expect that these differences will further diminish at later redshifts, a substantial delay may be sufficient to reduce the constraining power of the CMB. We furthermore find the oscillatory features present in the initial power spectrum are removed by nonlinear evolution, similar to the results found for ETHOS models with DAO at larger wavenumbers [96]. Lastly, we note that we ran a DAO simulation without running and found that the power spectra remains linear and the halofinder does not find any halos at this redshift.…”

“…7 shows the ratio of the DPS and DAO mass functions to the CDM one (note that this is done with the same mass bins, but plotted at the mean CDM mass per bin). We note that ETHOS models with DAO have oscillations in the halo mass function [96], which could be possible here, FIG. 6.…”

Mixed dark matter: matter power spectrum and halo mass function

“…[90] found that β = 4.8 and c = 3.3 provide a reasonable fit to N -body simulations, while Ref. [91] obtained comparable results (β = 3.0, c = 3.3) in scenarios where dark matter produces acoustic oscillations at small scales. We show our results in Figure 9.…”

Snowmass2021 Cosmic Frontier White Paper: Prospects for obtaining Dark Matter Constraints with DESI

“…axion-like particles, with extremely small masses m ∼ 10 −22 eV [69][70][71][72] (for an early discussion of the cosmological consequences of ultra-light boson particles for dark matter see also [73][74][75][76]) ; or of DM interactions described by e.g. the Lagrangianbased Effective theory of structure formation (ETHOS) [77,78]; or oscillations induced by interactions in the dark sector [72,[79][80][81]. The various beyond-CDM scenarios predict different shapes for the power spectrum suppressions: for example FDM and ETHOS predict oscillations at very small scales (for FDM see for instance [82,83]), contrarily to WDM.…”