The first WIMPy halos

By A. Green, S. Hofmann, D. Schwarz. 2005

266 citations recorded by the source corpus.

Dark matter direct and indirect detection signals depend crucially on the dark matter distribution. While the formation of large scale structure is independent of the nature of the cold dark matter (CDM), the fate of inhomogeneities on subgalactic scales, and hence the present day CDM distribution on these scales, depends on the microphysics of the CDM particles. We study the density contrast of weakly interacting massive particles (WIMPs) on subgalactic scales. We calculate the damping of the primordial power spectrum due to collisional damping and free streaming of WIMPy CDM and show that free streaming leads to a CDM power spectrum with a sharp cut-off at about . We also calculate the transfer function for the growth of the inhomogeneities in the linear regime, taking into account the suppression in the growth of the CDM density contrast after matter–radiation equality due to baryons and show that our analytic results are in good agreement with numerical calculations. Combining the transfer function with the damping of the primordial fluctuations we produce a WMAP normalized primordial CDM power spectrum, which can serve as an input for high resolution CDM simulations. We find that the smallest inhomogeneities typically have comoving radius of about 1 pc and enter the non-linear regime at a red-shift of 60 ± 20. We study the effect of scale dependence of the primordial power spectrum on these numbers and also use the spherical collapse model to make simple estimates of the properties of the first generation of WIMP halos to form. We find that the very first WIMPy halos may have a significant impact on indirect dark matter searches.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/ca3338d2aa360c4096087308b4b2d20bf34f8ac3

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

New production mechanism for keV sterile neutrino Dark Matter by decays of frozen-in scalars (2013, background): “However, between CDM and WDM there is not a very well-defined boundary, since it is not easy to unambiguously define at which value of rFS the structure formation on small scales starts to depart from the pure CDM case [7, 123, 124].”
Gravitational probes of dark matter physics (2017, background): “Free streaming can further damp the matter power spectrum, with [176]”
Constraints on dark matter annihilation in clusters of galaxies with the Fermi large area telescope (2010, background): “2 and Mcut = 10 −6 M⊙ [36] (even smaller cutoff scales are however possible in well-motivated WIMP scenarios [32] — see also [34] for a review).”
Limits on dark matter annihilation signals from the Fermi LAT 4-year measurement of the isotropic gamma-ray background (2015, background): “Such a cut-off exists, for example, due to the free streaming length of DM particles after kinetic decoupling [28, 29], which gives the highest frequency relevant Fourier mode kmax.”
Multi-frequency analysis of neutralino dark matter annihilations in the Coma cluster (2005, methodology): “1 the dependence of cvir on the halo mass M , at z = 0, according to the toy model of Bullock et al. (2001) as extrapolated down to the free-streaming mass scale for DM halos made of WIMPs, i.e. around 10−6M⊙ (see Hofmann et al. 2001, Chen et al. 2001, Green et al. 2005, Diemand et al. 2005).”
Hidden charged dark matter (2009, background): “For a typical WIMP with electroweak scale mass, the kinetic decoupling temperature ranges roughly from 10 MeV to 1 GeV, which leads to the formation of dark matter halos with masses as small as 10M⊙ to 10M⊙ [29–31, 51–55].”
The Dark Matter Annihilation Signal from Galactic Substructure: Predictions for GLAST (2008, background): “In principle this hierarchy could extend all the way down to the cut-off in the matter power spectrum, set by collisional damping and free streaming in the early universe (Green et al. 2005; Loeb & Zaldarriaga 2005).”
Characterization of subhalo structural properties and implications for dark matter annihilation signals (2016, background): “The minimum halo mass depends on the free-streaming of DM particles from high to low density regions (Zybin et al. 1999; Hofmann et al. 2001; Berezinsky et al. 2003; Green et al. 2005) and on the effect of acoustic oscillations (Loeb & Zaldarriaga 2005; Bertschinger 2006).”
Gamma Ray Signals from Dark Matter: Concepts, Status and Prospects (2012, background): “kinetic decoupling of WIMPs in the early Universe [104] and strongly depends on the DM particle properties [105, 106]; while in principle it could be as large as the scale of dwarf galaxies [107], it falls into the range of roughly 10−11–10−3 M⊙ for standard MSSM neutralinos [106] .”