Cosmological Simulations with Self-Interacting Dark Matter I: Constant Density Cores and Substructure

By Miguel Rocha, A. Peter, James S. Bullock, M. Kaplinghat, S. Garrison-Kimmel, J. Oñorbe, Leonidas A. Moustakas Center for Cosmology, D. Physics, Astronomy, U. California and 5 more. 2012

650 citations recorded by the source corpus.

We use cosmological simulations to study the effects of self-interacting dark matter (SIDM) on the density profiles and substructure counts of dark matte r halos from the scales of spiral galaxies to galaxy clusters, focusing explicitly on mod els with cross sections over dark matter particle mass σ/m = 1 and 0.1 cm 2 /g. Our simulations rely on a new SIDM N-body algorithm that is derived self-consistently from the Boltz mann equation and that reproduces analytic expectations in controlled numerical experiments. We find that well-resolved SIDM halos have constant-density cores, with significantly lowe r central densities than their CDM counterparts. In contrast, the subhalo content of SIDM halos is only modestly reduced compared to CDM, with the suppression greatest for large hosts and small halo-centric distances. Moreover, the large-scale clustering and halo circular vel ocity functions in SIDM are effectively identical to CDM, meaning that all of the large-scale successes of CDM are equally well matched by SIDM. From our largest cross section runs we are able to extract scaling relations for core sizes and central densities over a range o f halo sizes and find a strong correlation between the core radius of an SIDM halo and the NFW scale radius of its CDM counterpart. We construct a simple analytic model, based on CDM scaling relations, that captures all aspects of the scaling relations for SIDM halos. Our results show that halo core densities in σ/m = 1 cm 2 /g models are too low to match observations of galaxy clusters, low surface brightness spirals (LSBs), and dwarf spheroidal galaxies. However, SIDM with σ/m ≃ 0.1 cm 2 /g appears capable of reproducing reported core sizes and central densities of dwarfs, LSBs, and galaxy clusters without the need for velocity dependence. Higher resolution simulations over a wider range of masses will be required to confirm this expectation. We discuss constraints arising from the Bullet cluster observ ations, measurements of dark matter density on small-scales and subhalo survival requirements, and show that SIDM models with σ/m ≃ 0.1 cm 2 /g ≃ 0.2 barn/GeV are consistent with all observational constraints.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/334f755073d95d6cf2ee817d8e07b7430aa96686

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Nuclear and High Energy Physics

Citations in the corpus

The APOSTLE simulations: solutions to the Local Group's cosmic puzzles (2015, positive): “The lack of a single model able to reconcile all of the LG observations with CDM predictions has led to renewed interest in alternatives to CDM, such as warm (e.g. Lovell et al. 2012) or self-interacting dark matter (e.g. Rocha et al. 2013; Vogelsberger et al. 2014).”
Self-Interacting Dark Matter from a Non-Abelian Hidden Sector (2014, background): “Simulations [1] show that 〈v2 i 〉 ≈ (1.”
The impact of baryonic physics on the structure of dark matter haloes: the view from the FIRE cosmological simulations (2015, background): “However, recent SIDM models that take into account more accurate observational constraints and the effects of baryons offer promising explanation of the problem without violating any known observational constraints (Rocha et al. 2013; Peter et al. 2013; Kaplinghat et al. 2014; Elbert et al. 2015).”
Core formation in dwarf haloes with self-interacting dark matter: no fine-tuning necessary (2014, methodology): “Our SIDM implementation follows that described in Rocha et al. (2013), using a modified version of GADGET-2 (Springel, 2005).”
Too big to fail in the Local Group (2014, background): “Some authors have pointed out that self-interactions in the DM, possibly with a velocity-dependent cross-section (e.g. Zavala, Vogelsberger & Walker 2013), naturally lead to 0.5–1 kpc cores in dwarf subhaloes (Vogelsberger, Zavala & Loeb 2012; Rocha et al. 2013; Elbert et al., in preparation).”
Bound-state formation for thermal relic dark matter and unitarity (2014, neutral): “2 barn/GeV [45–48].”
Using the Milky Way satellites to study interactions between cold dark matter and radiation (2014, background): “However, one can understand the underlying physics by considering both the DM and radiation as interacting imperfect 1 We do not study self-interactions as these have been discussed already in Rocha et al. (2013).”
Galactic Searches for Dark Matter (2012, background): “Several groups have shown via N-body simulations that subhalos in this model are also less dense, and it is also more likely for the dSphs to populate the most massive subhalos of the Milky Way (Vogelsberger et al., 2012; Rocha et al., 2012; Peter et al., 2012).”
Dwarf galaxies in CDM and SIDM with baryons: observational probes of the nature of dark matter (2014, methodology): “The renewed interest in SIDM has triggered a new era of high-resolution DM-only SIDM simulations: velocity dependent in Vogelsberger, Zavala & Loeb (2012, hereafter VZL), and velocity independent in Rocha et al. (2013), that hint at a solution to the CDM problems in low-mass galaxies.”
The unexpected diversity of dwarf galaxy rotation curves (2015, background): “Available simulation data are sparse but suggest that the scatter in structural properties at fixed halo mass is no larger for alternative dark matter models than for CDM (e.g. Rocha et al. 2013; Lovell et al. 2014, for SIDM and WDM, respectively).”