Halo Formation in Warm Dark Matter Models

By Paul Bode, Jeremiah P. Ostriker, N. Turok. 2000

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Discrepancies have emerged between the predictions of standard cold dark matter (CDM) theory and observations of clustering on subgalactic scales. Warm dark matter (WDM) is a simple modification of CDM in which the dark matter particles have initial velocities due either to their having decoupled as thermal relics or to their having been formed via nonequilibrium decay. We investigate the nonlinear gravitational clustering of WDM with a high-resolution N-body code and identify a number of distinctive observational signatures. Relative to CDM, halo concentrations and core densities are lowered, core radii are increased, and large halos emerge with far fewer low-mass satellites. The number of small halos is suppressed, and those present are formed by "top-down" fragmentation of caustics, as part of a "cosmic web" connecting massive halos. Few small halos form outside this web. If we identify small halos with dwarf galaxies, then their number, spatial distribution, and formation epoch appear in better agreement with the observations for WDM than they are for CDM.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/f6b870034c42913b9742bd760990d7501bb34717

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Citations in the corpus

Cosmology and Fundamental Physics with the Euclid Satellite (2012, methodology): “The red line on Figure 37 shows the expected dark matter mass function for WDM with a (thermal relic) mass of mWDM = 1 keV.”
The First Stars (2003, background): “The first of these, the warm dark matter (WDM) model (e.g., Bode et al. 2001), has been proposed to remedy the well-known problems of standard CDM on subgalactic scales (e.g., Flores & Primack 1994, Moore et al. 1999).”
New production mechanism for keV sterile neutrino Dark Matter by decays of frozen-in scalars (2013, background): “nonrelativistic DM (CDM), provides a very good fit to the data [4], the intermediate case of warm Dark Matter (WDM) is still a valid possibility [5–10, 10–13].”
New Constraints on the free-streaming of warm dark matter from intermediate and small scale Lyman-$\alpha$ forest data (2017, background): “arise from the free-streaming of sterile neutrinos [22–24] or ultralight bosons [25], alternatives to the more generic thermal relics on which we concentrate our modeling here [26].”
Subhaloes in self-interacting galactic dark matter haloes (2012, background): “…models where DM is “warm”, i.e., where DM particles have larger primordial thermal velocities, are able to alleviate the overabundance problem (e.g. Bode et al. 2001; Zavala et al. 2009) and at the same time, if their masses are & 1 keV, avoid current constraints on the matter power spectrum as…”
Tests for Substructure in Gravitational Lenses (2003, background): “…that the incidence of anomalous flux ratios in gravitational lenses was consistent with the expected mass fraction of satellites found in cold dark matter (CDM) halo simulations (e.g., Kauffmann et al. 1993; Moore et al. 1999; Klypin et al. 1999; Bode et al. 2001; Zentner & Bullock 2003).”
The properties of warm dark matter haloes (2013, methodology): “N-body simulations with a resolved cutoff in the initial power spectrum undergo artificial fragmentation in filaments (Bode et al. 2001; Wang & White 2007).”
Lyman-alpha forests cool warm dark matter (2015, background): “When traveling, particles can interfere with the gravitational collapse of structures [2, 3, 10].”
Gravitational probes of dark matter physics (2017, background): “Originally, the cusp/core model motivated investigations into WDM models, because of their muchlower-than CDM primordial phase-space densities [273, 5].”
Understanding the shape and diversity of dwarf galaxy rotation curves in ΛCDM (2016, background): “…& Steinhardt 2000; Alcubierre et al. 2002; Zavala et al. 2013; Elbert et al. 2014; Magaña & Matos 2012), or weakly relativistic warm dark matter (e.g. Bode et al. 2001; AvilaReese et al. 2001; Strigari et al. 2007; Boyarsky et al. 2009; Villaescusa-Navarro & Dalal 2011; Macciò et al. 2012).”
The warm dark matter halo mass function below the cut-off scale (2013, methodology): “This phenomenon originates in the numerical (unphysical) fragmentation of filaments, and it exceeds by far the population of real WDM haloes on scales near the cut-off scale (see e.g. Avila-Reese et al. 2001; Bode et al. 2001; Wang & White 2007; Melott 2007).”