Scattering, damping, and acoustic oscillations: Simulating the structure of dark matter halos with relativistic force carriers

Abstract

We demonstrate that self-interacting dark matter models with interactions mediated by light particles can have significant deviations in the matter power spectrum and detailed structure of galactic halos when compared to a standard cold dark matter scenario. While these deviations can take the form of suppression of small-scale structure that are in some ways similar to that of warm dark matter, the self-interacting models have a much wider range of possible phenomenology. A long-range force in the dark matter can introduce multiple scales to the initial power spectrum, in the form of dark acoustic oscillations and an exponential cutoff in the power spectrum. Using simulations we show that the impact of these scales can remain observationally relevant up to the present day. Furthermore, the self-interaction can continue to modify the small-scale structure of the dark matter halos, reducing their central densities and creating a dark matter core. The resulting phenomenology is unique to these type of models.

BeyondΛCDM: Problems, solutions, and the road ahead

“…4.2), and this has in fact been the initial motivation for introducing SIDM models [350]. Although the extra damping (through selfinteraction [351] or collisions with standard particles such as radiation [352]) is a feature of various dark matter models, the existing large-scale structure constraints so far favor no observable deviations from the standard cold dark matter picture. Such deviations on very small scales may however be observable in the CMB [353], and can be looked for using future small-scale CMB experiments.…”

Dark matter–radiation interactions: the structure of Milky Way satellite galaxies

“…A range of alternatives to vanilla CDM have also been proposed e.g. warm DM (Schaeffer & Silk 1988), interacting DM (Boehm et al 2001;Boehm & Schaeffer 2005;Cyr-Racine & Sigurdson 2013;Chu & Dasgupta 2014), selfinteracting DM (Spergel & Steinhardt 2000;Rocha et al 2013;Vogelsberger et al 2014;Buckley et al 2014), decaying DM (Wang et al 2014) and late-forming DM (Agarwal et al 2015). These "beyond CDM" models generally exhibit a cut-off in the linear matter power spectrum at small scales (high wavenumbers) that translates into a reduced number of low-mass DM haloes compared to collisionless CDM at late times.…”

Dark Radiation Alleviates Problems with Dark Matter Halos

“…Quantitatively [47], we have M cut 1.7 × 10 8 (T kd /keV) −3 M , such that T kd 0.5 keV suppresses formation of DM protohalos smaller than about 10 9 M , and eases the missing satellites problem [48]. It is important to note that the acoustic damping cut-off in our model is different in shape (oscillatory, with powerlaw envelope) [49,50], from the free-streaming cut-off in warm dark matter models (exponential). As a result, Lyman-α and other constraints on warm dark matter [51,52] cannot be applied directly [49,50].…”

“…It is important to note that the acoustic damping cut-off in our model is different in shape (oscillatory, with powerlaw envelope) [49,50], from the free-streaming cut-off in warm dark matter models (exponential). As a result, Lyman-α and other constraints on warm dark matter [51,52] cannot be applied directly [49,50].…”