dark matterWe study the concentration of dark matter haloes and its evolution in N-body simulations of the standard cold dark matter (CDM) cosmology. The results presented in this paper are based on four large N-body simulations with 10 billion particles each: the Millennium-I and -II, ...
Without relying on a spherical or ellipsoidal collapse model, we analytically derive the halo mass function and cuspy halo density (inner slope of −4/3) based on the mass and energy cascade theory in dark matter flow. The hierarchical halo structure formation leads to halo or particle random...
We compare the central mass concentration of cold dark matter (CDM) halos found in cosmological N-body simulations with constraints derived from the Milky Way disk dynamics and from the Tully-Fisher relation. For currently favored values of the cosmological parameters (Ω~0.3 Λ=1-Ω~0.7 h~0.7...
We find an optimal fit at both small and large scales in terms of a halo constituted by an early body with α≈ 1.25 and by recent extensive outskirts, that make up an overall mass 10M with a concentration parameter c ≈ 10 consistent with the variance we compute in the ΛCDM cosmogony...
“To explain Draco’s high dark matter density, its initial halo concentration needs to be high,” she said. “More dark matter mass needs to be distributed in the inner halo. While this is true for both CDM and SIDM, for SIDM the core-collapse phenomenon can only occur if the concentra...
, are sensitive to the epoch of halo formation and tightly correlated with the halo virial parameters, via the concentration, c, and the virial overdensity ∆ vir . For example, the Navarro, Frenk, & White (1996, hereafter NFW) density profile has (α, β, γ) = (1, 3, 1). ...
The team then used the Keck Observatory to measure the speed of the mass concentration of galaxies in the clusters. Because most of this mass is accounted for by dark matter, it and galaxies as a whole behave similarly during the collision. Thus, this revealed to the researchers by proxy th...
Mapping Dark Matter This composite image of the merging galaxy cluster Abell 520 has superimposed, "false-colored" maps that show the cluster's concentration of starlight (orange), hot gas (green) and dark matter (much of the blue). Image courtesy NASA, ESA, CFHT, CXO, M.J. Jee (...
We find that at high redshifts the concentration falls to a minimum value of about 4.0 and then rises for higher values of halo mass鈥攁 new result. We present approximations for the velocity and mass functions of distinct halos as a function of redshift. We find that while the Sheth-...
We show how these decays will affect the halo mass-concentration relation and mass function. Using measurements of the halo mass-concentration relation and galaxy-cluster mass function to constrain the lifetime--kick-velocity parameter space for decaying dark matter, we find roughly that the ...