Virial Scaling of Massive Dark Matter Halos: Why Clusters Prefer a High Normalization Cosmology

• DOI: 10.1086/521616
• Publication Date: 2008-01-06T08:54:08Z
• Authors: A. E. Evrard; J. Bialek; M. Busha; M. White; S. Habib; K. Heitmann; M. Warren; E. Rasia; G. Tormen; L. Moscardini; C. Power; A. R. Jenkins; L. Gao; C. S. Frenk; V. Springel; S. D. M. White; J. Diemand
• Keywords: CMB cold spot; Virial mass; Velocity dispersion; Cold dark matter; Dimensionless quantity; Normalization

We present a precise estimate of the bulk virial scaling relation halos formed via hierarchical clustering in an ensemble simulated cold dark matter cosmologies. The result is insensitive to cosmological parameters; presence trace, dissipationless gas component; and numerical resolution down limit ~1000 particles. velocity dispersion scales with total mass as log [σDM(M,z)] = log(1082.9 ± 4.0 km s−1) + (0.3361 0.0026)log[h(z)M200/1015 M☉], h(z) being dimensionless Hubble parameter. At fixed mass, likelihood nearly lognormal, scatter σln σ 0.0426 0.015, except for tail higher dispersions containing 10% population that are merger transients. combine this halo function ΛCDM models show low normalization condition, S8 σ8(Ωm/0.3)0.35 0.69, favored by recent WMAP SDSS analysis requires galaxy gas-specific energies rich clusters be 50% larger than underlying matter. Such large energetic biases conflict current generation direct simulations cluster formation. A normalization, 0.80, alleviates tension implies hot fraction within r500 , value consistent Sunyaev-Zel'dovich observations.