Small scale clustering of late forming dark matter

Abstract

We perform a study of the nonlinear clustering of matter in the late-forming dark matter (LFDM) scenario in which dark matter results from the transition of a nonminimally coupled scalar field from radiation to collisionless matter. A distinct feature of this model is the presence of a damped oscillatory cutoff in the linear matter power spectrum at small scales. We use a suite of high-resolution N-body simulations to study the imprints of LFDM on the nonlinear matter power spectrum, the halo mass and velocity functions and the halo density profiles. The model largely satisfies high-redshift matter power spectrum constraints from Lyman-$\alpha$ forest measurements, while it predicts suppressed abundance of low-mass halos ($\sim 10^{9}-10^{10}$ h$^{-1}$ M$_\odot$) at all redshifts compared to a vanilla $\Lambda$CDM model. The analysis of the LFDM halo velocity function shows a better agreement than the $\Lambda$CDM prediction with the observed abundance of low-velocity galaxies in the local volume. Halos with mass $M\gtrsim 10^{11}$ h$^{-1}$ M$_\odot$ show minor departures of the density profiles from $\Lambda$CDM expectations, while smaller-mass halos are less dense, consistent with the fact that they form later than their $\Lambda$CDM counterparts.Comment: 13 pages, 7 figures, 1 table, added analysis from higher resolution simulation

Dark matter–radiation interactions: the impact on dark matter haloes

“…We highlight the differences with respect to CDM and in addition, warm DM (WDM), which shows a qualitatively similar suppression of power on small scales (Schaeffer & Silk 1988). We note that recent work has also considered non-linear SF in a number of alternative models such as self-interacting DM (Rocha et al 2013;Vogelsberger et al 2014), decaying DM (Wang et al 2014), late-forming DM (Agarwal et al 2014), atomic DM (Cyr-Racine & Sigurdson 2013) and DM interacting with dark radiation (Buckley et al 2014;Chu & Dasgupta 2014); see also Schneider (2014).…”

The ALP miracle revisited

“…Also, it was shown in ref. [65] that the suppression of the small-scale structure in the late-forming dark matter scenario could lead to a better agreement with the observed number of the dwarf galaxies and relax the missing satellite problem [66,67] if…”

Structure formation with suppressed small-scale perturbations

“…Other possibilities with similar effects on small scales are (Agarwal et al 2014), or ultra-light axion DM (Marsh & Silk 2013). It is also possible to obtain suppressed small-scale perturbations from effects not related to dark matter.…”